feat(state): BoosterInventoryNotifier

lib/state/booster_inventory_notifier.dart

@@ -0,0 +1,28 @@
+// lib/state/booster_inventory_notifier.dart
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../data/save_repository.dart';
+import '../game/models/booster.dart';
+import 'providers.dart';
+
+/// Live booster counts backed by [SaveRepository]. State is an immutable map.
+class BoosterInventoryNotifier extends Notifier<Map<BoosterType, int>> {
+  SaveRepository get _save => ref.read(saveRepositoryProvider);
+
+  @override
+  Map<BoosterType, int> build() => _snapshot();
+
+  Map<BoosterType, int> _snapshot() =>
+      {for (final t in BoosterType.values) t: _save.boosterCount(t)};
+
+  Future<void> grant(BoosterType type, [int n = 1]) async {
+    await _save.grantBooster(type, n);
+    state = _snapshot();
+  }
+
+  Future<bool> consume(BoosterType type) async {
+    final ok = await _save.consumeBooster(type);
+    if (ok) state = _snapshot();
+    return ok;
+  }
+}

lib/state/providers.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../data/content_repository.dart';
 import '../data/save_repository.dart';
 import '../data/streak.dart';
+import '../game/models/booster.dart';
 import '../game/models/season.dart';
 import '../services/ad_service.dart';
 import '../services/analytics_service.dart';
@@ -13,6 +14,7 @@ import '../services/music_service.dart';
 import '../services/review_service.dart';
 import '../services/store_reviewer.dart';
 import 'ads_notifier.dart';
+import 'booster_inventory_notifier.dart';
 import 'endless_best_notifier.dart';
 import 'music_notifier.dart';
 import 'sound_notifier.dart';
@@ -143,3 +145,8 @@ final activeThemeProvider = Provider<SeasonTheme>((ref) {
   final flow = ref.watch(seasonFlowProvider);
   return flow?.pack.theme ?? SeasonTheme.fallback;
 });
+
+final boosterInventoryProvider =
+    NotifierProvider<BoosterInventoryNotifier, Map<BoosterType, int>>(
+  BoosterInventoryNotifier.new,
+);