Go service that reads a USB webcam via V4L2, overlays OctoPrint stats (state, filename, temps, progress, ETA) on one stream, and publishes both raw and overlay feeds to MediaMTX via RTSP for WebRTC/HLS/RTSP fan-out. Includes web UI, systemd units, and installer script. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>