reconciler: generic resource state machine — BFS pathfinding from current
to wanted state, dependency constraints, event/periodic tick model.
reconciler_cli exercises it with simulated device/transport/stream resources.
ingest: V4L2 capture module — open device, negotiate MJPEG format, MMAP
buffer pool, capture thread with on_frame callback. start/stop lifecycle
designed for reconciler management. Transport-agnostic: caller wires
on_frame to proto_write_video_frame.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
