feat(settings): soundEnabled provider gates SFX and haptics

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/state/providers.dart

@@ -11,6 +11,7 @@ import '../services/consent_service.dart';
 import '../services/iap_service.dart';
 import 'ads_notifier.dart';
 import 'endless_best_notifier.dart';
+import 'sound_notifier.dart';
 import 'game_session_notifier.dart';
 import 'progress_notifier.dart';
 import 'season_flow_notifier.dart';
@@ -22,8 +23,12 @@ final gameSessionProvider =
   GameSessionNotifier.new,
 );
 
+final soundEnabledProvider =
+    NotifierProvider<SoundEnabledNotifier, bool>(SoundEnabledNotifier.new);
+
 final audioServiceProvider = Provider<AudioService>((ref) {
-  final service = AudioService();
+  final service = AudioService(enabled: ref.read(soundEnabledProvider));
+  ref.listen<bool>(soundEnabledProvider, (_, next) => service.enabled = next);
   ref.onDispose(service.dispose);
   return service;
 });

lib/state/sound_notifier.dart

@@ -0,0 +1,17 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'providers.dart';
+
+/// SFX + gameplay haptics on/off, seeded from the save repository.
+class SoundEnabledNotifier extends Notifier<bool> {
+  @override
+  bool build() => ref.read(saveRepositoryProvider).soundEnabled;
+
+  Future<void> toggle() => set(!state);
+
+  Future<void> set(bool value) async {
+    if (state == value) return;
+    await ref.read(saveRepositoryProvider).setSoundEnabled(value);
+    state = value;
+  }
+}