Mirror the desktop video pipeline into the #[cfg(target_os="android")] start
function: capture _negotiated_video_codec from the handshake, spawn a video
send task that pulls VideoFrames from camera_tx, encodes/packetizes/sends.
Add video reassembly + decode + emit "video:frame" in the recv task before
the audio branch so Android can both send and receive video.
Instrumentation: emit video:first_send and video:first_recv on both desktop
and android paths so we can verify the pipeline end-to-end.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
25b3278d31