test(helpers): 테스트 헬퍼 및 Fake 스토리지 추가

- TestSetup 클래스 추가 (SharedPreferences 모킹, 싱글톤 정리)
- FakeHallOfFameStorage: 메모리 기반 명예의 전당 저장소
- FakeStatisticsStorage: 메모리 기반 통계 저장소
- path_provider 의존성 없이 테스트 가능하도록 개선

test/helpers/mock_factories.dart

@@ -4,12 +4,16 @@ import 'package:asciineverdie/src/core/engine/reward_service.dart';
 import 'package:asciineverdie/src/core/model/combat_state.dart';
 import 'package:asciineverdie/src/core/model/combat_stats.dart';
 import 'package:asciineverdie/src/core/model/game_state.dart';
+import 'package:asciineverdie/src/core/model/game_statistics.dart';
+import 'package:asciineverdie/src/core/model/hall_of_fame.dart';
 import 'package:asciineverdie/src/core/model/monetization_state.dart';
 import 'package:asciineverdie/src/core/model/monster_combat_stats.dart';
 import 'package:asciineverdie/src/core/model/pq_config.dart';
+import 'package:asciineverdie/src/core/storage/hall_of_fame_storage.dart';
 import 'package:asciineverdie/src/core/storage/save_manager.dart';
 import 'package:asciineverdie/src/core/storage/save_repository.dart';
 import 'package:asciineverdie/src/core/storage/save_service.dart';
+import 'package:asciineverdie/src/core/storage/statistics_storage.dart';
 import 'package:asciineverdie/src/core/util/balance_constants.dart';
 
 export 'package:asciineverdie/src/core/storage/save_repository.dart'
@@ -201,3 +205,91 @@ class MockFactories {
     );
   }
 }
+
+/// 테스트용 Fake HallOfFameStorage
+///
+/// 파일 시스템 접근 없이 메모리에서 동작
+class FakeHallOfFameStorage extends HallOfFameStorage {
+  HallOfFame _hallOfFame = HallOfFame.empty();
+
+  @override
+  Future<HallOfFame> load() async => _hallOfFame;
+
+  @override
+  Future<bool> save(HallOfFame hallOfFame) async {
+    _hallOfFame = hallOfFame;
+    return true;
+  }
+
+  @override
+  Future<bool> addEntry(HallOfFameEntry entry) async {
+    _hallOfFame = _hallOfFame.addEntry(entry);
+    return true;
+  }
+
+  @override
+  Future<bool> deleteEntry(String id) async {
+    _hallOfFame = _hallOfFame.removeEntry(id);
+    return true;
+  }
+
+  @override
+  Future<bool> clear() async {
+    _hallOfFame = HallOfFame.empty();
+    return true;
+  }
+}
+
+/// 테스트용 Fake StatisticsStorage
+///
+/// 파일 시스템 접근 없이 메모리에서 동작
+class FakeStatisticsStorage extends StatisticsStorage {
+  CumulativeStatistics _stats = CumulativeStatistics.empty();
+
+  @override
+  Future<CumulativeStatistics> loadCumulative() async => _stats;
+
+  @override
+  Future<bool> saveCumulative(CumulativeStatistics stats) async {
+    _stats = stats;
+    return true;
+  }
+
+  @override
+  Future<bool> mergeSession(SessionStatistics session) async {
+    _stats = _stats.mergeSession(session);
+    return true;
+  }
+
+  @override
+  Future<bool> updateHighestLevel(int level) async {
+    if (level <= _stats.highestLevel) return true;
+    _stats = _stats.updateHighestLevel(level);
+    return true;
+  }
+
+  @override
+  Future<bool> updateHighestGold(int gold) async {
+    if (gold <= _stats.highestGoldHeld) return true;
+    _stats = _stats.updateHighestGold(gold);
+    return true;
+  }
+
+  @override
+  Future<bool> recordGameStart() async {
+    _stats = _stats.recordGameStart();
+    return true;
+  }
+
+  @override
+  Future<bool> recordGameComplete() async {
+    _stats = _stats.recordGameComplete();
+    return true;
+  }
+
+  @override
+  Future<bool> clear() async {
+    _stats = CumulativeStatistics.empty();
+    return true;
+  }
+}