✨ WebRTC signaling heartbeat

lib/pods/chat/webrtc_signaling.dart

@@ -57,6 +57,7 @@ class WebRTCSignaling {
   final StreamController<WebRTCWelcomeMessage> _welcomeController =
       StreamController<WebRTCWelcomeMessage>.broadcast();
   WebSocketChannel? _channel;
+  Timer? _heartbeatTimer;
 
   Stream<SignalingMessage> get messages => _messageController.stream;
   Stream<WebRTCWelcomeMessage> get welcomeMessages => _welcomeController.stream;
@@ -88,6 +89,9 @@ class WebRTCSignaling {
       }
       await _channel!.ready;
 
+      // Start heartbeat timer
+      _heartbeatTimer = Timer.periodic(const Duration(seconds: 30), (timer) => _sendHeartbeat());
+
       _channel!.stream.listen(
         (data) {
           final dataStr =
@@ -196,7 +200,15 @@ class WebRTCSignaling {
     );
   }
 
+  void _sendHeartbeat() {
+    if (_channel == null) return;
+    talker.info('[WebRTC Signaling] Sending heartbeat');
+    final packet = WebSocketPacket(type: 'heartbeat', data: null);
+    _channel!.sink.add(jsonEncode(packet.toJson()));
+  }
+
   void disconnect() {
+    _heartbeatTimer?.cancel();
     _channel?.sink.close();
     _messageController.close();
     _welcomeController.close();