spatial.py: Triangulates sound source position from two DoA angles using
ray intersection. Exponential smoothing prevents jitter. Gaze drifts back
to center after 2s of silence. Converts position (mm) to gaze (0-255).
headmic.py: Replaces simple doa_poll_loop with doa_track_loop that runs
the spatial tracker and pushes gaze to the eye service when the position
changes. Rate-limited to 10 pushes/sec with minimum delta threshold.
/doa endpoint now returns triangulated position + gaze coordinates.
Array separation (175mm) stored in config, overridable.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
