feat: 초기 커밋

- Progress Quest 6.4 Flutter 포팅 프로젝트
- 게임 루프, 상태 관리, UI 구현
- 캐릭터 생성, 인벤토리, 장비, 주문 시스템
- 시장/판매/구매 메커니즘

lib/src/core/storage/save_manager.dart

@@ -0,0 +1,33 @@
+import 'package:askiineverdie/src/core/model/game_state.dart';
+import 'package:askiineverdie/src/core/model/save_data.dart';
+import 'package:askiineverdie/src/core/storage/save_repository.dart';
+import 'package:askiineverdie/src/core/storage/save_service.dart'
+    show SaveFileInfo;
+
+/// Coordinates saving/loading GameState using SaveRepository.
+class SaveManager {
+  SaveManager(this._repo);
+
+  final SaveRepository _repo;
+  static const String defaultFileName = 'progress.pqf';
+
+  /// Save current game state to disk. [fileName] may be absolute or relative.
+  /// Returns outcome with error on failure.
+  Future<SaveOutcome> saveState(GameState state, {String? fileName}) {
+    final save = GameSave.fromState(state);
+    return _repo.save(save, fileName ?? defaultFileName);
+  }
+
+  /// Load game state from disk. [fileName] may be absolute (e.g., file picker).
+  /// Returns outcome + optional state.
+  Future<(SaveOutcome, GameState?)> loadState({String? fileName}) async {
+    final (outcome, save) = await _repo.load(fileName ?? defaultFileName);
+    if (!outcome.success || save == null) {
+      return (outcome, null);
+    }
+    return (outcome, save.toState());
+  }
+
+  /// 저장 파일 목록 조회
+  Future<List<SaveFileInfo>> listSaves() => _repo.listSaves();
+}

lib/src/core/storage/save_repository.dart

@@ -0,0 +1,64 @@
+import 'dart:io';
+
+import 'package:askiineverdie/src/core/model/save_data.dart';
+import 'package:askiineverdie/src/core/storage/save_service.dart';
+import 'package:path_provider/path_provider.dart';
+
+class SaveOutcome {
+  const SaveOutcome.success([this.error]) : success = true;
+  const SaveOutcome.failure(this.error) : success = false;
+
+  final bool success;
+  final String? error;
+}
+
+/// High-level save/load wrapper that resolves platform storage paths.
+class SaveRepository {
+  SaveRepository() : _service = null;
+
+  SaveService? _service;
+
+  Future<void> _ensureService() async {
+    if (_service != null) return;
+    final dir = await getApplicationSupportDirectory();
+    _service = SaveService(baseDir: dir);
+  }
+
+  Future<SaveOutcome> save(GameSave save, String fileName) async {
+    try {
+      await _ensureService();
+      await _service!.save(save, fileName);
+      return const SaveOutcome.success();
+    } on FileSystemException catch (e) {
+      final reason = e.osError?.message ?? e.message;
+      return SaveOutcome.failure('Unable to save file: $reason');
+    } catch (e) {
+      return SaveOutcome.failure(e.toString());
+    }
+  }
+
+  Future<(SaveOutcome, GameSave?)> load(String fileName) async {
+    try {
+      await _ensureService();
+      final data = await _service!.load(fileName);
+      return (const SaveOutcome.success(), data);
+    } on FileSystemException catch (e) {
+      final reason = e.osError?.message ?? e.message;
+      return (SaveOutcome.failure('Unable to load save: $reason'), null);
+    } on FormatException catch (e) {
+      return (SaveOutcome.failure('Corrupted save file: ${e.message}'), null);
+    } catch (e) {
+      return (SaveOutcome.failure(e.toString()), null);
+    }
+  }
+
+  /// 저장 파일 목록 조회
+  Future<List<SaveFileInfo>> listSaves() async {
+    try {
+      await _ensureService();
+      return await _service!.listSaves();
+    } catch (e) {
+      return [];
+    }
+  }
+}

lib/src/core/storage/save_service.dart

@@ -0,0 +1,84 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:askiineverdie/src/core/model/save_data.dart';
+
+/// Persists GameSave as JSON compressed with GZipCodec.
+class SaveService {
+  SaveService({required this.baseDir});
+
+  final Directory baseDir;
+  final GZipCodec _gzip = GZipCodec();
+
+  Future<File> save(GameSave save, String fileName) async {
+    final path = _resolvePath(fileName);
+    final file = File(path);
+    await file.parent.create(recursive: true);
+    final jsonStr = jsonEncode(save.toJson());
+    final bytes = utf8.encode(jsonStr);
+    final compressed = _gzip.encode(bytes);
+    return file.writeAsBytes(compressed);
+  }
+
+  Future<GameSave> load(String fileName) async {
+    final path = _resolvePath(fileName);
+    final file = File(path);
+    final compressed = await file.readAsBytes();
+    final decompressed = _gzip.decode(compressed);
+    final jsonStr = utf8.decode(decompressed);
+    final map = jsonDecode(jsonStr) as Map<String, dynamic>;
+    return GameSave.fromJson(map);
+  }
+
+  String _resolvePath(String fileName) {
+    final normalized = fileName.endsWith('.pqf') ? fileName : '$fileName.pqf';
+    final file = File(normalized);
+    if (file.isAbsolute) return file.path;
+    return '${baseDir.path}/$normalized';
+  }
+
+  /// 저장 디렉토리의 모든 .pqf 파일 목록 반환
+  Future<List<SaveFileInfo>> listSaves() async {
+    if (!await baseDir.exists()) {
+      return [];
+    }
+
+    final files = <SaveFileInfo>[];
+    await for (final entity in baseDir.list()) {
+      if (entity is File && entity.path.endsWith('.pqf')) {
+        final stat = await entity.stat();
+        final name = entity.uri.pathSegments.last;
+        files.add(
+          SaveFileInfo(
+            fileName: name,
+            fullPath: entity.path,
+            modifiedAt: stat.modified,
+            sizeBytes: stat.size,
+          ),
+        );
+      }
+    }
+
+    // 최근 수정된 파일 순으로 정렬
+    files.sort((a, b) => b.modifiedAt.compareTo(a.modifiedAt));
+    return files;
+  }
+}
+
+/// 저장 파일 정보
+class SaveFileInfo {
+  const SaveFileInfo({
+    required this.fileName,
+    required this.fullPath,
+    required this.modifiedAt,
+    required this.sizeBytes,
+  });
+
+  final String fileName;
+  final String fullPath;
+  final DateTime modifiedAt;
+  final int sizeBytes;
+
+  /// 확장자 없는 표시용 이름
+  String get displayName => fileName.replaceAll('.pqf', '');
+}