Risolve timeout creazione sessione YouTube lato app.

La setup broadcast YouTube (~23s) passa in background job; l'API risponde
subito. Aumentato anche il timeout Dio mobile per createSession YouTube.

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

mobile/lib/shared/api_client.dart

@@ -167,6 +167,10 @@ class ApiClient {
     int? targetBitrate,
     int? targetFps,
   }) async {
+    // YouTube: creazione broadcast + path MediaMTX può richiedere 20–30s lato server.
+    final sessionTimeout = platform == 'youtube'
+        ? const Duration(seconds: 60)
+        : const Duration(seconds: 30);
     final response = await _dio.post<Map<String, dynamic>>(
       '/matches/$matchId/sessions',
       data: {
@@ -177,6 +181,10 @@ class ApiClient {
         if (targetBitrate != null) 'target_bitrate': targetBitrate,
         if (targetFps != null) 'target_fps': targetFps,
       },
+      options: Options(
+        sendTimeout: sessionTimeout,
+        receiveTimeout: sessionTimeout,
+      ),
     );
     return StreamSession.fromJson(response.data!);
   }