Corregge avvio RTMP bloccato dopo errore o cambio sessione.

Il motore Android ignorava startStream in CONNECTING/RECONNECTING; la camera
ora resetta prima di pubblicare. YouTube relay parte solo con overlay attivo.

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

mobile/lib/features/camera_mode/camera_screen.dart

@@ -165,7 +165,11 @@ class _CameraScreenState extends ConsumerState<CameraScreen> {
               fresh.status == 'live' ||
               fresh.status == 'reconnecting');
       if (shouldAutoPublish) {
-        await Future<void>.delayed(const Duration(milliseconds: 500));
+        // Reset motore nativo (sessione precedente / RECONNECTING blocca startStream).
+        try {
+          await StreamingChannel.stopStream();
+        } catch (_) {}
+        await Future<void>.delayed(const Duration(milliseconds: 400));
         final useFreshStart =
             justStartedSession || fresh.status == 'connecting';
         if (useFreshStart) {
@@ -497,6 +501,7 @@ class _CameraScreenState extends ConsumerState<CameraScreen> {
     _statsTimer?.cancel();
     _scorePullTimer?.cancel();
     _metricsSub?.cancel();
+    unawaited(StreamingChannel.stopStream());
     WakelockPlus.disable();
     _unlockOrientation();
     super.dispose();