Wire season flow: map screen, progress save, win recording, next stage

SaveRepository (versioned JSON over prefs) with best-result merging and
unlock walking; ContentRepository loads the bundled pack; SeasonFlow/
Progress notifiers orchestrate stage start -> win record -> advance.
Season map grid with stars/locks, Home -> Map -> Game navigation,
close button, next-stage action on the win overlay.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/state/providers.dart

@@ -1,7 +1,12 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../data/content_repository.dart';
+import '../data/save_repository.dart';
+import '../game/models/season.dart';
 import '../services/audio_service.dart';
 import 'game_session_notifier.dart';
+import 'progress_notifier.dart';
+import 'season_flow_notifier.dart';
 
 final gameSessionProvider =
     NotifierProvider<GameSessionNotifier, GameViewState?>(
@@ -13,3 +18,24 @@ final audioServiceProvider = Provider<AudioService>((ref) {
   ref.onDispose(service.dispose);
   return service;
 });
+
+/// Overridden with the opened repository in main() (and in tests).
+final saveRepositoryProvider = Provider<SaveRepository>(
+  (ref) => throw UnimplementedError('override with an opened SaveRepository'),
+);
+
+final progressProvider =
+    NotifierProvider<ProgressNotifier, Map<String, StageProgress>>(
+  ProgressNotifier.new,
+);
+
+final seasonFlowProvider = NotifierProvider<SeasonFlowNotifier, SeasonFlow?>(
+  SeasonFlowNotifier.new,
+);
+
+final contentRepositoryProvider =
+    Provider<ContentRepository>((ref) => ContentRepository());
+
+final seasonsProvider = FutureProvider<List<SeasonPack>>(
+  (ref) => ref.read(contentRepositoryProvider).availableSeasons(),
+);