flow_id is now optional (config().contains). When absent: skip the
MXL reader, active-wait, and NDI video path entirely. Video buffers
and NDI video frames are heap-allocated only when has_video.
Loop pacing: video branch sleeps 1ms on TOO_EARLY as before; audio-only
path sleeps 1ms when no chunk was available (audio_advanced == false)
to avoid busy-spinning.
NDI sender name changed from the video flow UUID to node_id(), which
is stable and human-readable for both video and audio-only modes.
To use audio-only: wire only audio_flow_id in build_graph, omit flow_id.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
JohannesItten
5504b8983e