feat(adr-117/p3+p3.5): vitals + BFLD bindings

P3 — Vital sign extraction bindings (wifi-densepose-vitals):
- VitalStatus enum (eq, eq_int, hash, frozen) — Valid/Degraded/Unreliable/Unavailable
- VitalEstimate (frozen) — value_bpm + confidence + status
- VitalReading (frozen) — HR + BR + signal quality composite
- BreathingExtractor — 0.1–0.5 Hz bandpass + zero-crossing
- HeartRateExtractor — 0.8–2.0 Hz bandpass + autocorrelation
- py.allow_threads on extract() hot loops (Q5 audit confirmed
  core/vitals/signal are pure-sync — zero tokio deps, safe to release
  GIL with no embedded runtime needed)
- 17 tests covering construction, getters, frozen immutability,
  esp32_default + explicit ctors, synthetic-signal end-to-end

P3.5 — BFLD bindings (forward-compat surface, stub Rust):
- BfldKind enum — CompressedHE20/40/80/160 + UncompressedHT20/40
  with n_subcarriers, bandwidth_mhz, is_he metadata getters
- BfldFrame (frozen) — from_compressed_feedback() accepts numpy
  Complex64 ndarray [Nr x Nc x Nsc], validates dims against kind,
  feedback_matrix() returns lossless roundtrip ndarray
- BfldReport — aggregates frames, rejects mismatched kinds,
  computes inverse-CV coherence score
- 19 tests covering all 6 PHY variants + numpy roundtrip +
  dim-mismatch error + aggregation
- Real Rust ingestion (wifi-densepose-bfld crate) lands post-v2.0
  per ADR-117 §11.11/12 — Python API will not change

Total Python test count: 93 (was 57, +36 P3+P3.5). All passing.

Refs: docs/adr/ADR-117-pip-wifi-densepose-modernization.md
Refs: #785

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

python/README.md

@@ -49,13 +49,24 @@ python/
 
 ## Phase status (per ADR-117 §6)
 
-- ✅ **P1 — Scaffold (this commit)**: module loads, version constant
-  exposed, 6 smoke tests pass via `maturin develop`.
-- ⏳ **P2 — Core type bindings**: `CsiFrame`, `Keypoint`, `PoseEstimate`.
-- ⏳ **P3 — Vitals + signal DSP**: 4-stage HR/BR pipeline + `CsiProcessor`
-  + `PhaseSanitizer`, with `allow_threads` GIL release on hot loops.
+- ✅ **P1 — Scaffold**: module loads, version constant exposed,
+  6 smoke tests pass via `maturin develop`.
+- ✅ **P2 — Core type bindings**: `Keypoint`, `KeypointType`,
+  `BoundingBox`, `PersonPose`, `PoseEstimate`. 51 additional tests.
+- ✅ **P3 — Vitals + signal DSP**: `VitalStatus`, `VitalEstimate`,
+  `VitalReading`, `BreathingExtractor`, `HeartRateExtractor` with
+  `py.allow_threads` GIL release on hot loops (Q5 tokio audit on
+  2026-05-24 confirmed core/vitals/signal are pure-sync). 17 tests.
+- ✅ **P3.5 — BFLD bindings (stub Rust)**: `BfldKind`, `BfldFrame`,
+  `BfldReport` — forward-compatible Python surface for 802.11ac/ax/be
+  Beamforming Feedback Loop Data. numpy Complex64 bridge. 19 tests.
+  Real Rust ingestion lands post-v2.0 in a `wifi-densepose-bfld`
+  crate (see ADR-117 §11.11/12); the Python API does not change.
 - ⏳ **P4 — WS/MQTT client**: pure-Python `wifi_densepose.client` extra.
 - ⏳ **P5 — cibuildwheel + PyPI publish**: Linux/macOS/Windows × abi3-py310.
+- ⏳ **P-tomb — v1.99.0 tombstone wheel**: pure-Python ImportError
+  with migration URL, published to PyPI to soft-fence v1.x users
+  before v2.0 ships.
 
 Each phase ends with a checkbox PR. Tests are additive — every phase's
 smoke tests must still pass after later phases land.