Stabilizza live YouTube/RTMP e fix crash rotazione mobile.

Pipeline YouTube con relay, overlay e publisher sync lato backend; fix GL pauseGlDuringRotation su Android per evitare crash in rotazione durante lo streaming Flutter.

Co-authored-by: Cursor <cursoragent@cursor.com>

mobile/lib/shared/websocket_service.dart

@@ -26,6 +26,7 @@ class WebsocketService {
   ActionCable? _cable;
   ActionChannel? _channel;
   String? _sessionId;
+  Future<void>? _connectOp;
 
   bool get isConnected => _cable != null && _channel != null;
 
@@ -35,6 +36,24 @@ class WebsocketService {
   }) async {
     if (_sessionId == sessionId && isConnected) return;
 
+    final prev = _connectOp;
+    if (prev != null) await prev.catchError((_) {});
+
+    _connectOp = _connect(sessionId: sessionId, deviceRole: deviceRole);
+    final op = _connectOp!;
+    try {
+      await op;
+    } finally {
+      if (identical(_connectOp, op)) {
+        _connectOp = null;
+      }
+    }
+  }
+
+  Future<void> _connect({
+    required String sessionId,
+    required String deviceRole,
+  }) async {
     await disconnect();
 
     final token = _ref.read(authProvider).accessToken;
@@ -161,11 +180,20 @@ class WebsocketService {
   }
 
   Future<void> disconnect() async {
-    _channel?.unsubscribe();
+    final channel = _channel;
+    final cable = _cable;
     _channel = null;
-    _cable?.disconnect();
     _cable = null;
     _sessionId = null;
+
+    try {
+      channel?.unsubscribe();
+    } catch (_) {}
+    try {
+      cable?.disconnect();
+    } catch (_) {}
+
+    await Future<void>.delayed(const Duration(milliseconds: 150));
     _ref.read(sessionProvider.notifier).setConnected(false);
   }