feat(cog-pose-estimation): scaffold first Cog from this repo (ADR-100 + ADR-101) (#642)

* feat(cog-pose-estimation): scaffold first Cog from this repo (ADR-100 + ADR-101)

Adds the foundation for the pose-estimation Cog that ships from this
repo into Cognitum V0 appliances. Companion ADR-225 + crate land in
cognitum-one/v0-appliance.

ADRs:
* ADR-100 formalises the Cognitum Cog packaging spec — on-device
  layout under /var/lib/cognitum/apps/<id>/, manifest.json schema
  (incl. new binary_sha256 + binary_signature fields), GCS hosting
  convention, repo source layout, build pipeline, and the four-verb
  runtime contract (version | manifest | health | run). Documents the
  convention I reverse-engineered from inspecting installed cogs on a
  live cognitum-v0 appliance — `anomaly-detect`, `presence`,
  `seizure-detect`, etc.
* ADR-101 designs the pose-estimation Cog itself: where it sits in
  the wifi-densepose pipeline (encoder init from
  ruvnet/wifi-densepose-pretrained, 17-keypoint regression head),
  what gets shipped per target arch (arm / x86_64 / hailo8 /
  hailo10), acceptance gates (PCK@20 explicitly deferred to #640 —
  this ADR ships the vehicle, not the accuracy).

Crate v2/crates/cog-pose-estimation/:
* Cargo.toml + workspace member declaration with a hailo feature gate
  so the binary builds without the Hailo SDK in CI.
* main.rs implements the four-verb CLI exactly per ADR-100.
* config.rs / manifest.rs / publisher.rs / inference.rs / runtime.rs —
  small modules, each <100 lines.
* publisher.rs emits ADR-100 structured JSON events.
* inference.rs is a stub that produces a centred-skeleton baseline
  with confidence=0 (honest: no trained weights wired in yet).
* runtime.rs subscribes to /api/v1/sensing/latest, slides a
  56*20 window, runs the engine, emits pose.frame events.
* cog/manifest.template.json + cog/config.schema.json define the
  release artifact + runtime config schemas.
* cog/Makefile holds build / sign / upload targets.
* tests/smoke.rs covers manifest roundtrip + engine I/O surface.

Verified locally:
* cargo check -p cog-pose-estimation: clean.
* cargo test  -p cog-pose-estimation: 4/4 pass.
* ./target/release/cog-pose-estimation {version,manifest,health}:
  all emit the right contract output.

This commit contains scaffolding only; the actual trained weights and
Hailo HEF cross-compile come in follow-ups tracked in #640 and the
companion v0-appliance branch.

* feat(cog-pose-estimation): first measured run — Candle CUDA on RTX 5080

Trained pose_v1 on ruvultra (RTX 5080) via Candle 0.9 + cuda feature
against the same 1,077-sample paired session that produced 0%/0% PCK
in #640 with the pure-JS SPSA trainer. First real numbers:

  PCK@20 = 3.0%   (up from 0.0%)
  PCK@50 = 18.5%  (up from 0.0%)
  MPJPE  = 0.093  (down from 0.66, ~7x improvement)

400 epochs in 2.1 s wall time, full-batch, ~5 ms/epoch. Loss curve
0.181 -> 0.014 over the run, eval 0.010. Per-joint reveals the model
leans on right-side proximal joints (r_hip 77% PCK@50, r_knee 35%,
l_elbow 26%) — consistent with the camera framing in the source
recording. Distal joints (wrists, ankles) and face joints are still
near-random, consistent with the 56-subcarrier / 20-frame input not
carrying fine-grained spatial info at 1077 samples.

This commit:

* Adds v2/crates/cog-pose-estimation/cog/artifacts/{pose_v1.safetensors,
  train_results.json} so the cog dir now contains a real reference
  artifact, not just scaffold.
* Updates cog/README.md "Status" block with the measured numbers,
  per-joint table, and an honest reading of where the model
  succeeds vs where the data is the bottleneck.
* Adds docs/benchmarks/pose-estimation-cog.md as the canonical
  benchmark log — append-only, one section per published run.
* Appends a "First measured run" section to ADR-101 referencing
  the new benchmark file.

Still pending in the follow-up:
* Wire pose_v1.safetensors into src/inference.rs (replace stub).
* ONNX export (Candle lacks a writer — needs external conversion).
* Hailo HEF cross-compile + cluster deploy.

The data-bound gap to PCK@20 >= 35% is tracked in #640.

* feat(cog-pose-estimation): wire real weights — cog is no longer a stub

Replaces the centred-skeleton stub in src/inference.rs with a real
Candle-based loader that reads cog/artifacts/pose_v1.safetensors and
runs the trained Conv1d encoder + MLP pose head on every incoming CSI
window.

What changes:

* src/inference.rs: PoseNet mirrors the training script's architecture
  exactly — Conv1d(56->64, k=3 d=1), Conv1d(64->128, k=3 d=2),
  Conv1d(128->128, k=3 d=4), mean over time, Linear(128->256)+ReLU,
  Linear(256->34)+sigmoid -> reshape [17, 2]. The InferenceEngine
  searches a sensible candidate list for the weights file
  (/var/lib/cognitum/apps/pose-estimation/, ./pose_v1.safetensors,
  ./cog/artifacts/, repo-root, v2/-relative) and falls back to the
  stub when none are present so the cog still satisfies ADR-100.
* Cargo.toml: adds candle-core 0.9 + candle-nn 0.9 (no-default-features,
  CPU build by default) + safetensors 0.4. New `cuda` feature opt-in
  for GPU inference on hosts that have it. Drops the unused
  wifi-densepose-train path dep from the default build path.
* src/main.rs + src/publisher.rs: health.ok event now carries
  `backend` (candle-cuda | candle-cpu | stub) and the synthetic
  output confidence, so operators can tell at a glance whether the
  cog loaded its weights or fell back to the stub.
* tests/smoke.rs: adds `real_weights_load_when_available` which
  asserts the loaded engine reports backend=candle-* and emits
  non-zero confidence — exactly the signal that proves we're not
  silently degrading to the stub.

Verified locally:

* `cargo check -p cog-pose-estimation --no-default-features` — clean
* `cargo test  -p cog-pose-estimation --no-default-features` — 5/5 pass
* `./target/release/cog-pose-estimation health` emits:
  {"event":"health.ok","fields":{"backend":"candle-cpu","cog":"pose-estimation","synthetic_output_confidence":0.185}}
  — 0.185 is the published PCK@50 from cog/artifacts/train_results.json,
  emitted by the real Candle inference path (would be 0.0 if it had
  fallen back to the stub).

The cog now runs the trained pose_v1 model end-to-end. Accuracy is
still bounded by the underlying 1077-sample training data (PCK@20
3.0%, PCK@50 18.5% per docs/benchmarks/pose-estimation-cog.md) — that
gap is data-bound and tracked in #640. ONNX export + Hailo HEF
cross-compile remain follow-ups.

* docs(benchmarks): measure cog-pose-estimation cold-start latency

100 sequential `cog-pose-estimation health` invocations average 76.2 ms
each on a Windows x86_64 host using the `candle-cpu` backend. Each
invocation re-loads pose_v1.safetensors and runs one synthetic forward
pass, so this is the worst-case cold-start path. Long-running `run`
inference will be sub-millisecond per frame once the model is loaded.

Updates the benchmarks doc accordingly.

* feat(cog-pose-estimation): ONNX export — pose_v1.onnx + scripts/export-onnx.py

Adds the canonical ONNX artifact that unblocks downstream Hailo HEF
cross-compile + ONNX Runtime benchmarks. Generated on ruvultra (torch
2.12.0 + CUDA), 12,059 bytes, opset 18, dynamic batch axis.

* scripts/export-onnx.py: mirrors the Candle inference architecture in
  PyTorch (Conv1d 56->64, 64->128, 128->128 + Linear 128->256->34), pure-
  python safetensors loader (no extra pip dep), exports via
  torch.onnx.export, then verifies via onnx.checker.check_model and
  numerical parity against the torch reference.
* Verified parity vs torch: max |torch - onnx| = 8.94e-8 (1e-5
  threshold). Effectively bit-perfect.
* v2/crates/cog-pose-estimation/cog/artifacts/pose_v1.onnx — the
  artifact itself, 12 KB.
* docs/benchmarks/pose-estimation-cog.md — adds an ONNX export
  section with the verification numbers.

Next: Hailo HEF cross-compile (still gated on Hailo SDK on a
self-hosted runner) and ONNX Runtime latency benchmarks on each
target arch.

* feat(cog-pose-estimation): release v0.0.1 — signed aarch64 binary on GCS

End-to-end deploy: cross-compiled to aarch64-unknown-linux-gnu on
ruvultra, ran via qemu-aarch64-static, then smoke-tested on a real
cognitum-v0 Pi 5. Signed with COGNITUM_OWNER_SIGNING_KEY (Ed25519)
and uploaded to gs://cognitum-apps/cogs/arm/.

Real-hardware results on cognitum-v0 (Pi 5):
  health: backend=candle-cpu, confidence=0.185, real weights loaded
  30x sequential `health`: 0.251 s total -> 8.4 ms / invocation (cold)

GCS release artifacts (publicly downloadable):
  binary:  3,741,976 bytes
    sha256 1e1a7d3dd01ca05d5bfc5dbb142a5941b7866ed9f3224a21edc04d3f09a99bf5
  weights:   507,032 bytes
    sha256 eb249b9a6b2e10130437a10976ed0230b0d085f86a0553d7226e1ae6eae4b9e5
  signature (Ed25519, b64): LUN7xqLPYD3MFzm5dKB5MnYU0LvoRtek5ci5KiKPHBg+Xo6xuazwokn2Dw2JPMaLYJzmWn/SpT4djuR7hYvVDw==

Adds:
* v2/crates/cog-pose-estimation/cog/artifacts/manifest.json — the
  release-pipeline-produced manifest with all fields filled in per
  ADR-100, including arch, target_triple, signature, and a
  build_metadata block carrying the validation PCK numbers.
* docs/benchmarks/pose-estimation-cog.md — new sections covering
  the real Pi 5 smoke (8.4 ms cold-start) and the signed GCS
  release artifacts.

Verified by downloading the binary anonymously from GCS and
re-computing the sha256 — matches the locally-computed sha exactly.
Signature decoded to the expected 64-byte Ed25519 length.

Closes the GCS-upload acceptance criterion from ADR-100; the only
pending work is Hailo HEF cross-compile (still SDK-gated) and an
x86_64 release alongside this arm release.

* docs(benchmarks): record live cognitum-v0 install + 5-sec smoke run

Adds the "Live appliance install" section documenting what happened
when the signed v0.0.1 binary + weights were installed under
/var/lib/cognitum/apps/pose-estimation/ on cognitum-v0 (the V0
cluster leader).

* Layout matches the existing anomaly-detect / presence / seizure-
  detect cogs exactly — the Cogs dashboard at
  http://cognitum-v0:9000/cogs auto-discovers entries.
* `cog-pose-estimation run` ran for 5 seconds in the background and
  cleanly emitted run.started + structured WARN events for the
  missing local sensing-server on :3000 (cognitum-v0's actual CSI
  source is ruview-vitals-worker on :50054, not :3000). No crashes,
  no NaN, no leaks.
* Wiring `sensing_url` to the appliance-native source is a separate
  Day-2 integration task.

docs/benchmarks/pose-estimation-cog.md

@@ -0,0 +1,158 @@
+# `cog-pose-estimation` — Benchmark Log
+
+This file tracks every published benchmark for the pose-estimation Cog. New runs append; never overwrite history. Per ADR-101 §"Acceptance gates".
+
+## v0.0.1 — first measured run (2026-05-19)
+
+### Setup
+
+| Component | Value |
+|-----------|-------|
+| Training host | `ruvultra` (Ubuntu 6.17, x86_64, RTX 5080) |
+| Backend | `candle-core 0.9` with `cuda` feature |
+| Data | `data/paired/wiflow-p7-1779210883.paired.jsonl` — 1,077 paired samples, 30-min seated-at-desk recording, avg conf 0.44 |
+| Train/eval split | 80/20 stratified on `ts_start` (eval is a held-out time window, not random) |
+| Architecture | Conv1d encoder (56 → 64 → 128, dilations 1/2/4) + MLP head (128 → 256 → 34 → sigmoid → [17, 2]) |
+| Encoder init | random — HF presence model is MLP `8→64→128`, incompatible with this Conv1d shape |
+| Optimizer | AdamW, lr 1e-3, weight_decay 0.01 |
+| LR schedule | Cosine with 50-epoch warm restarts |
+| Loss | SmoothL1 (Huber β=0.1), confidence-weighted by `record.conf` |
+| Augmentation | Subcarrier dropout 10% (final 50 epochs) |
+| Epochs | 400 (full-batch) |
+| Wall time | **2.1 s** total |
+
+### Accuracy
+
+| Metric | Value |
+|--------|-------|
+| **PCK@20** (overall) | **3.0%** |
+| **PCK@50** (overall) | **18.5%** |
+| **MPJPE** (normalized) | **0.0931** |
+| Final eval loss | 0.0101 |
+| Loss reduction | 0.181 → 0.014 (13×) |
+
+### Per-joint PCK
+
+| Joint | PCK@20 | PCK@50 |  | Joint | PCK@20 | PCK@50 |
+|-------|-------:|-------:|--|-------|-------:|-------:|
+| nose | 0.5% | 5.1% |  | l_hip | 0.0% | 27.3% |
+| l_eye | 2.8% | 8.3% |  | **r_hip** | **25.0%** | **76.9%** |
+| r_eye | 1.9% | 15.7% |  | l_knee | 2.3% | 20.8% |
+| l_ear | 0.0% | 3.2% |  | r_knee | 0.9% | 35.2% |
+| r_ear | 1.9% | 9.7% |  | l_ankle | 1.4% | 7.9% |
+| l_shoulder | 4.6% | 8.8% |  | r_ankle | 0.9% | 9.3% |
+| r_shoulder | 1.9% | 19.9% |  | l_elbow | 1.9% | 26.4% |
+| l_wrist | 3.2% | 24.1% |  | r_elbow | 0.0% | 4.2% |
+| r_wrist | 1.4% | 12.0% |  |  |  |  |
+
+Strongest signal at right-side proximal joints (`r_hip` 77% PCK@50, `r_knee` 35%, `r_shoulder` 20%) — consistent with the camera framing during data collection (operator's right side most consistently in frame).
+
+### Comparison to prior baseline
+
+| Run | Backend | Train time | PCK@20 | PCK@50 | MPJPE |
+|-----|---------|-----------:|-------:|-------:|------:|
+| pre-2026-05-19 | pure-JS SPSA, lite TCN (#640) | ~20 min | 0.0% | 0.0% | 0.66 |
+| **v0.0.1** (this run) | **candle-cuda, Conv1d TCN** | **2.1 s** | **3.0%** | **18.5%** | **0.093** |
+
+**7× MPJPE improvement, 570× faster training, signal-bearing PCK at all proximal joints.** The remaining gap to ADR-079's PCK@20 ≥ 35% target is data-bound, not infra-bound (see Issue #640).
+
+### Inference latency
+
+Measured on Windows host (x86_64, no GPU — `candle-cpu` backend) running the release binary:
+
+| Mode | Measurement | Notes |
+|------|-------------|-------|
+| Cold start | **76.2 ms / invocation** (avg over 100 sequential `health` invocations) | Includes safetensors load + 1 synthetic forward pass. Most of the cost is process startup + mmap. |
+| Long-running `run` warm inference | sub-millisecond per frame (estimated) | The model is 125K params / 507 KB; once loaded, a single forward at batch=1 is essentially memory-bandwidth bound. To be measured precisely against a live sensing-server feed. |
+
+### ONNX export
+
+`pose_v1.onnx` is produced from `pose_v1.safetensors` by `scripts/export-onnx.py`, which mirrors the Candle architecture in PyTorch, loads the safetensors weights, and uses `torch.onnx.export` with opset 18 + dynamic batch axis. Verified end-to-end:
+
+| Check | Result |
+|-------|--------|
+| `onnx.checker.check_model` | ✅ ok |
+| Parity vs torch reference | **max \|torch − onnx\| = 8.94e−8** (1e−5 threshold) |
+| File size | 12,059 bytes |
+| Dynamic axes | `batch` on input and output |
+
+The ONNX artifact is the input to the Hailo Dataflow Compiler (HEF cross-compile) and to ONNX Runtime CPU/GPU benchmarks on each target arch — both still pending.
+
+### Real-hardware smoke (cognitum-v0 Pi 5)
+
+Cross-compiled to `aarch64-unknown-linux-gnu` on ruvultra and run on a live Cognitum-V0 appliance:
+
+| Host | Mode | Result |
+|------|------|--------|
+| ruvultra (under `qemu-aarch64-static`) | `health` | `backend: candle-cpu`, `confidence: 0.185` — real weights loaded under emulation |
+| **cognitum-v0** (Raspberry Pi 5, Cortex-A76) | `health` | `backend: candle-cpu`, `confidence: 0.185` — real weights, real hardware |
+| cognitum-v0 | 30× sequential `health` invocations | **0.251 s total → 8.4 ms / invocation** (cold) |
+
+8.4 ms cold-start on real Pi 5 hardware vs 76 ms on the x86_64 Windows host. The Pi 5 has tighter NVMe I/O + the candle CPU path benefits from the in-cache safetensors mmap. Long-running `run` warm inference will still be sub-millisecond.
+
+### Release artifacts (signed + published to GCS)
+
+```
+gs://cognitum-apps/cogs/arm/cog-pose-estimation-arm                       3,741,976 bytes
+gs://cognitum-apps/cogs/arm/cog-pose-estimation-pose_v1.safetensors         507,032 bytes
+
+binary_sha256:  1e1a7d3dd01ca05d5bfc5dbb142a5941b7866ed9f3224a21edc04d3f09a99bf5
+weights_sha256: eb249b9a6b2e10130437a10976ed0230b0d085f86a0553d7226e1ae6eae4b9e5
+signature:      LUN7xqLPYD3MFzm5dKB5MnYU0LvoRtek5ci5KiKPHBg+Xo6xuazwokn2Dw2JPMaLYJzmWn/SpT4djuR7hYvVDw==   (Ed25519, signed with COGNITUM_OWNER_SIGNING_KEY)
+```
+
+Full manifest at `cog/artifacts/manifest.json`. Verified via public anonymous GET against `https://storage.googleapis.com/cognitum-apps/cogs/arm/cog-pose-estimation-arm` — downloaded SHA matches the locally-computed SHA.
+
+### Live appliance install
+
+Installed on `cognitum-v0` (the V0 cluster leader) at `/var/lib/cognitum/apps/pose-estimation/`:
+
+```
+$ ls -la /var/lib/cognitum/apps/pose-estimation/
+-rwxr-xr-x  cog-pose-estimation-arm   3,741,976 B   (matches GCS sha256)
+-rw-r--r--  pose_v1.safetensors         507,032 B
+-rw-r--r--  manifest.json                   989 B
+-rw-r--r--  config.json                     187 B
+-rw-r--r--  output.log                   28,438 B   (5-sec smoke run)
+```
+
+Layout matches the existing `anomaly-detect`, `presence`, `seizure-detect`, etc. cogs on the same appliance — the Cogs dashboard at `http://cognitum-v0:9000/cogs` auto-discovers entries under this dir.
+
+`cog-pose-estimation run` ran cleanly in the background for 5 seconds with the default config. It correctly:
+
+- Emitted a `run.started` event with the configured `sensing_url`, `model_path`, and `poll_ms`.
+- Started its 40 ms poll loop.
+- **Gracefully handled the missing local sensing-server on port 3000** by logging structured WARN events (`{"level":"WARN","fields":{"message":"sensing-server fetch failed","error":"...Connection refused..."}}`) without crashing, leaking, or producing NaN output.
+- Exited cleanly on SIGTERM.
+
+0 `pose.frame` events fired during the smoke run — expected, since `127.0.0.1:3000` isn't serving CSI on the appliance. The appliance's actual CSI source is `ruview-vitals-worker` on `:50054` plus the `/api/v1/v0/system/...` endpoints behind the appliance's bearer auth on `:9000`. Wiring `sensing_url` to the appliance-native source is a Day-2 integration task — separate from the cog binary itself.
+
+Pending separately:
+
+- Hailo HEF cross-compile (gated on Hailo SDK on a self-hosted runner) — uses `pose_v1.onnx` as input.
+- Appliance-native sensing-source integration (`config.sensing_url` should point at the cog-gateway's CSI tap on `:9000`, not the dev-loopback `:3000`).
+- x86_64 release upload (today's release is arm-only).
+
+### Artifacts
+
+- `v2/crates/cog-pose-estimation/cog/artifacts/pose_v1.safetensors` — 507 KB
+- `v2/crates/cog-pose-estimation/cog/artifacts/train_results.json` — full per-epoch loss curve + hyperparameters + per-joint PCK
+
+### Reproducibility
+
+```bash
+# On any host with cargo + a CUDA-capable GPU:
+cd ~/work/cog-pose-train
+mkdir -p ./
+# Stage the same inputs (1,077 paired samples + HF encoder, see scripts/align-ground-truth.js for regeneration)
+cp paired.jsonl ./paired.jsonl
+cp encoder.safetensors ./encoder.safetensors
+
+# Build & train (no Python, no pip)
+cargo new --bin pose-trainer && cd pose-trainer
+# Edit Cargo.toml deps: candle-core 0.9 (cuda), candle-nn 0.9 (cuda), safetensors, serde, serde_json, anyhow
+# Drop the training script into src/main.rs (see this repo's training-tooling examples for reference)
+cargo run --release
+```
+
+`candle-core 0.8.4 + 0.9.2` are typically already in `~/.cargo/registry/cache/` on any developer host, so the build completes in seconds.