fix: live demo static pose & inaccurate sensing data (issue #86)

- Docker default changed from --source simulated to --source auto
  (auto-detects ESP32 on UDP 5005, falls back to simulation)
- Pose derivation now driven by real sensing features: motion_band_power,
  breathing_band_power, variance, dominant_freq_hz, change_points
- Temporal feature extraction: 100-frame circular buffer, Goertzel
  breathing rate estimation (0.1-0.5 Hz), frame-to-frame L2 motion
  detection, SNR-based signal quality metric
- Signal field driven by subcarrier variance spatial mapping instead
  of fixed animation circle
- UI data source indicators: LIVE/RECONNECTING/SIMULATED banner on
  sensing tab, estimation mode badge on live demo tab
- Setup guide panel explaining ESP32 count requirements for each
  capability level (1x: presence, 3x: localization, 4x+: full pose)
- Tick rate improved from 500ms to 100ms (2fps to 10fps)
- Fixed Option<f64> division bug from PR #83
- ADR-035 documents all decisions

Closes #86

Co-Authored-By: claude-flow <ruv@ruv.net>

docs/adr/ADR-035-live-sensing-ui-accuracy.md

@@ -0,0 +1,75 @@
+# ADR-035: Live Sensing UI Accuracy & Data Source Transparency
+
+## Status
+Accepted
+
+## Date
+2026-03-02
+
+## Context
+
+Issue #86 reported that the live demo shows a static/barely-animated stick figure and the sensing page displays inaccurate data, despite a working ESP32 sending real CSI frames. Investigation revealed three root causes:
+
+1. **Docker defaults to `--source simulated`** — even with a real ESP32 connected, the server generates synthetic sine-wave data instead of reading UDP frames.
+2. **Live demo pose is analytically computed** — `derive_pose_from_sensing()` generates keypoints using `sin(tick)` math unrelated to actual signal content. No trained `.rvf` model is loaded by default.
+3. **Sensing feature extraction is oversimplified** — the server uses single-frame thresholds for motion detection and has no temporal analysis (breathing FFT, sliding window variance, frame history).
+4. **No data source indicator** — users cannot tell whether they are seeing real or simulated data.
+
+## Decision
+
+### 1. Docker: Auto-detect data source
+- Default `CSI_SOURCE` changed from `simulated` to `auto`.
+- `auto` probes UDP port 5005 for an ESP32; falls back to simulation if none found.
+- Users override via `CSI_SOURCE=esp32 docker-compose up`.
+
+### 2. Signal-responsive pose derivation
+- `derive_pose_from_sensing()` now reads actual sensing features:
+  - `motion_band_power` drives limb splay and walking gait detection (> 0.55).
+  - `breathing_band_power` drives torso expansion/contraction phased to breathing rate.
+  - `variance` seeds per-joint noise so the skeleton moves independently.
+  - `dominant_freq_hz` drives lateral torso lean.
+  - `change_points` add burst jitter to extremity keypoints.
+- Tick rate reduced from 500ms to 100ms (2 fps → 10 fps).
+- `pose_source` field (`signal_derived` | `model_inference`) added to every WebSocket frame.
+
+### 3. Temporal feature extraction
+- 100-frame circular buffer (`VecDeque`) added to `AppStateInner`.
+- Per-subcarrier temporal variance via Welford-style accumulation.
+- Breathing rate estimation via 9-candidate Goertzel filter bank (0.1–0.5 Hz) with 3x SNR gate.
+- Frame-to-frame L2 motion score replaces single-frame amplitude thresholds.
+- Signal quality metric: SNR-based (RSSI − noise floor) blended with temporal stability.
+- Signal field driven by subcarrier variance spatial mapping instead of fixed animation.
+
+### 4. Data source transparency in UI
+- **Sensing tab**: Banner showing "LIVE - ESP32" (green), "RECONNECTING..." (yellow), or "SIMULATED DATA" (red).
+- **Live Demo tab**: "Estimation Mode" badge showing "Signal-Derived" (green) or "Model Inference" (blue).
+- **Setup Guide** panel explaining what each ESP32 count provides (1x: presence/breathing, 3x: localization, 4x+: full pose with trained model).
+- Simulation fallback delayed from immediate to 5 failed reconnect attempts (~30s).
+
+## Consequences
+
+### Positive
+- Users with real ESP32 hardware get real data by default (auto-detect).
+- Simulated data is clearly labeled — no more confusion about data authenticity.
+- Pose skeleton visually responds to actual signal changes (motion, breathing, variance).
+- Feature extraction produces physiologically meaningful metrics (breathing rate via Goertzel, temporal motion detection).
+- Setup guide manages expectations about what each hardware configuration provides.
+
+### Negative
+- Signal-derived pose is still an approximation, not neural network inference. Per-limb tracking requires a trained `.rvf` model + 4+ ESP32 nodes.
+- Goertzel filter bank adds ~O(9×N) computation per frame (negligible at 100 frames).
+- Users with only 1 ESP32 may still be disappointed that arm tracking doesn't work — but the UI now explains why.
+
+## Files Changed
+- `docker/Dockerfile.rust` — `CSI_SOURCE=auto` env, shell entrypoint for variable expansion
+- `docker/docker-compose.yml` — `CSI_SOURCE=${CSI_SOURCE:-auto}`, shell command string
+- `wifi-densepose-sensing-server/src/main.rs` — frame history buffer, Goertzel breathing estimation, temporal motion score, signal-driven pose derivation, pose_source field, 100ms tick default
+- `ui/services/sensing.service.js` — `dataSource` state, delayed simulation fallback, `_simulated` marker
+- `ui/components/SensingTab.js` — data source banner, "About This Data" card
+- `ui/components/LiveDemoTab.js` — estimation mode badge, setup guide panel
+- `ui/style.css` — banner, badge, and guide panel styles
+
+## References
+- Issue: https://github.com/ruvnet/wifi-densepose/issues/86
+- ADR-029: RuvSense multistatic sensing mode (proposed — full pipeline integration)
+- ADR-014: SOTA signal processing