Fix audio playback: add room.startAudio() call

Root cause: Audio from remote participant (Julia AI) was not playing
because room.startAudio() was never called after connecting.

This is REQUIRED by LiveKit WebRTC to enable audio playback.
The fix matches the working implementation in debug.tsx (Robert version).

Changes:
- Add room.startAudio() call after room.connect()
- Add canPlayAudio state tracking
- Add proper error handling for startAudio

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

hooks/useLiveKitRoom.ts

@@ -435,6 +435,19 @@ export function useLiveKitRoom(options: UseLiveKitRoomOptions): UseLiveKitRoomRe
 
       logSuccess('Connected to room!');
 
+      // ========== CRITICAL: Start Audio Playback ==========
+      // This is REQUIRED for audio to play on iOS and Android!
+      // Without this call, remote audio tracks will NOT be heard.
+      logInfo('Starting audio playback (room.startAudio)...');
+      try {
+        await lkRoom.startAudio();
+        logSuccess(`Audio playback started! canPlaybackAudio: ${lkRoom.canPlaybackAudio}`);
+        setCanPlayAudio(lkRoom.canPlaybackAudio);
+      } catch (audioPlaybackErr: any) {
+        logError(`startAudio failed: ${audioPlaybackErr.message}`);
+        // Don't fail the whole call - audio might still work on some platforms
+      }
+
       // Check if connection was cancelled after connect
       if (isUnmountingRef.current || currentConnectionId !== connectionIdRef.current) {
         logWarn('Connection cancelled after room.connect()');