fix(ios): recover AVAudioSession after phone call interruption

[ashifali3147]

Fix: Reliable Audio Session Recovery for Cellular Calls on iOS 16+

Problem

iOS 16+ does not reliably fire AVAudioSessionInterruptionTypeEnded for cellular calls, leaving WebRTC's audio unit dormant despite the mic appearing enabled. This causes one-way audio or complete audio loss.

Affected scenarios:

• Cellular call interruptions
• Dynamic Island calls
• App backgrounding during calls

Solution

Implement multi-source interrupt recovery using three notification channels:

1. Interruption Notification – Standard AVAudioSession interruption ended
2. App Active Notification – App returns to foreground after backgrounding
3. Route Change Notification – Dynamic Island & audio route switches

Recovery clears the interrupted flag only when RTCAudioSession.setActive() succeeds, enabling automatic retry on failures.

Changes

New RoomEvents

RoomEvents.audioSessionInterruptedEvent  // Fired on interruption
RoomEvents.audioSessionResumedEvent      // Fired on successful recovery

Flutter Example

roomEvents.audioSessionInterruptedEvent.listen((_) {
  room.localParticipant?.setMicrophoneEnabled(false);
});

roomEvents.audioSessionResumedEvent.listen((_) {
  room.localParticipant?.setMicrophoneEnabled(true);
});

Key Benefits

• Handles cellular calls, Dynamic Island, and backgrounding
• State-safe recovery with intelligent retry
• No premature state resets during route changes
• Observable events for UI feedback
• Fully backward compatible

Testing

• Cellular call interruption → audio restores
• Dynamic Island call → audio recovers
• App backgrounding + cellular call → works on foreground return
• Route changes (Bluetooth, speaker) → no dropout
• Event firing → both events fire correctly

---

Fixes audio loss on iOS 16+ during cellular call interruptions.

[ashifali3147]

Windows build failure is pre-existing and unrelated to this PR — same failure appears on other recent PRs (e.g. 1091 ). All other checks pass.