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>

docker/Dockerfile.rust

@@ -42,5 +42,15 @@ EXPOSE 5005/udp
 
 ENV RUST_LOG=info
 
-ENTRYPOINT ["/app/sensing-server"]
-CMD ["--source", "simulated", "--tick-ms", "100", "--ui-path", "/app/ui", "--http-port", "3000", "--ws-port", "3001"]
+# CSI_SOURCE controls which data source the sensing server uses at startup.
+# auto      — probe UDP port 5005 for an ESP32 first; fall back to simulation (default)
+# esp32     — receive real CSI frames from an ESP32 device over UDP port 5005
+# wifi      — use host Wi-Fi RSSI/scan data (Windows netsh; not available in containers)
+# simulated — generate synthetic CSI frames (no hardware required)
+# Override at runtime:  docker run -e CSI_SOURCE=esp32 ...
+ENV CSI_SOURCE=auto
+
+ENTRYPOINT ["/bin/sh", "-c"]
+# Shell-form CMD allows $CSI_SOURCE to be substituted at container start.
+# The ENV default above (CSI_SOURCE=auto) applies when the variable is unset.
+CMD ["/app/sensing-server --source ${CSI_SOURCE} --tick-ms 100 --ui-path /app/ui --http-port 3000 --ws-port 3001"]