Screen shares and game shares can sit static for long stretches — a still
desktop, a paused video, a code editor with no caret movement. The
encoder genuinely stops emitting RTP, the subscriber's track goes muted,
and the 15s camera window would falsely reap the live tile.
watchVideoTrackForRemoval now takes a per-call windowMs; the sub-PC
ontrack handler passes VIDEO_REMOVE_MUTE_WINDOW_SCREEN_MS (120s) for
screen + game and VIDEO_REMOVE_MUTE_WINDOW_MS (15s) for camera. A
genuine unshare still resolves through the 'ended' path within a
frame, so the longer window only affects the slow-failure case.
Tests bumped to 18: new screen-window assertions + invalid-windowMs
fallback to the default rather than disabling removal entirely.
Russell Ballestrini
0878996e96