Aggiunge overlay server-side burn-in e stabilizza diretta live.

Tabellone, badge e brand sono ricodificati nel flusso _air via OverlayRelay;
sync punteggio HTTP, volume condiviso rails/sidekiq, qualità 720p migliorata
e badge CONNECTING in ripresa da pausa.

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

mobile/lib/providers/score_sync_provider.dart

@@ -0,0 +1,77 @@
+import 'dart:async';
+
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../shared/api_client.dart';
+import '../shared/models/score_state.dart';
+import 'score_provider.dart';
+import 'session_provider.dart';
+
+/// Coda sync HTTP: evita richieste fuori ordine e allinea l'app al DB (pagina live).
+class ScoreSyncService {
+  ScoreSyncService(this._ref);
+
+  final Ref _ref;
+  bool _busy = false;
+  bool _dirty = false;
+  DateTime? _suppressStaleRemoteUntil;
+
+  /// Ignora broadcast WebSocket obsoleti subito dopo un push HTTP.
+  bool acceptCableScore(ScoreState remote) {
+    final until = _suppressStaleRemoteUntil;
+    if (until == null || DateTime.now().isAfter(until)) return true;
+    final local = _ref.read(scoreProvider);
+    return !_isClearlyBehind(remote, local);
+  }
+
+  bool _isClearlyBehind(ScoreState remote, ScoreState local) {
+    final r = remote.homeSets * 1000 +
+        remote.awaySets * 1000 +
+        remote.homePoints +
+        remote.awayPoints;
+    final l = local.homeSets * 1000 +
+        local.awaySets * 1000 +
+        local.homePoints +
+        local.awayPoints;
+    return r < l;
+  }
+
+  Future<void> push() async {
+    _dirty = true;
+    if (_busy) return;
+    _busy = true;
+    while (_dirty) {
+      _dirty = false;
+      final sessionId = _ref.read(sessionProvider).session?.id;
+      if (sessionId == null) continue;
+
+      final payload = _ref.read(scoreProvider).toCablePayload();
+      try {
+        final remote = await _ref.read(apiClientProvider).syncScore(sessionId, payload);
+        _suppressStaleRemoteUntil = DateTime.now().add(const Duration(milliseconds: 500));
+        if (remote != null) {
+          _ref.read(scoreProvider.notifier).applyRemote(remote);
+        }
+      } catch (_) {
+        // Mantieni stato locale; il prossimo pull periodico riallinea se possibile.
+      }
+    }
+    _busy = false;
+  }
+
+  Future<void> pullFromServer() async {
+    if (_busy) return;
+    final sessionId = _ref.read(sessionProvider).session?.id;
+    if (sessionId == null) return;
+    try {
+      final session = await _ref.read(apiClientProvider).fetchSession(sessionId);
+      if (session.score != null) {
+        _ref.read(scoreProvider.notifier).applyRemote(session.score!);
+      }
+    } catch (_) {}
+  }
+}
+
+final scoreSyncProvider = Provider<ScoreSyncService>((ref) {
+  return ScoreSyncService(ref);
+});