AudioManager.setScreenShareActive(true) was firing before the browser's screen
picker, killing the mic stream. The picker suspends getUserMedia while its secure
overlay is open, trapping the mic in a dead state for 5-30s. Now the AEC rebuild
fires after the track is acquired — mic stays alive during the picker.
Root cause: degradationPreference 'maintain-resolution' forced FPS drops under CPU
pressure during fast-motion gaming. Changed to 'maintain-framerate' so the encoder
drops resolution temporarily instead of stuttering. Added contentHint='motion' to
optimize for temporal prediction (more P-frames, fewer I-frames).
Screen sharing was publishing at h360 (640x360) and never ramping to target
resolution due to stale closure in setTimeout, wrong initial quality anchor,
and 5 competing code paths with inconsistent bitrates.
- Create utils/screenShare.ts as single source of truth for all screen share ops
- Publish at target resolution from the start (not h360 → ramp)
- Read store at call time in timers (eliminates stale closure bug)
- Use maintain-resolution for screen content, maintain-framerate for camera
- Fix OS-level "Stop sharing" not resetting store or restoring AEC
- Enable dynacast for SFU quality signaling
- Reconcile QUALITY_MAP to canonical bitrates across all 7 files