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/engine/progress_loop.dart

@@ -0,0 +1,138 @@
+import 'dart:async';
+
+import 'package:askiineverdie/src/core/model/game_state.dart';
+import 'package:askiineverdie/src/core/storage/save_manager.dart';
+import 'package:askiineverdie/src/core/engine/progress_service.dart';
+
+class AutoSaveConfig {
+  const AutoSaveConfig({
+    this.onLevelUp = true,
+    this.onQuestComplete = true,
+    this.onActComplete = true,
+    this.onStop = true,
+  });
+
+  final bool onLevelUp;
+  final bool onQuestComplete;
+  final bool onActComplete;
+  final bool onStop;
+
+  bool shouldSave(ProgressTickResult result) {
+    return (onLevelUp && result.leveledUp) ||
+        (onQuestComplete && result.completedQuest) ||
+        (onActComplete && result.completedAct);
+  }
+}
+
+/// Runs the periodic timer loop that advances tasks/quests/plots.
+class ProgressLoop {
+  ProgressLoop({
+    required GameState initialState,
+    required this.progressService,
+    this.saveManager,
+    Duration tickInterval = const Duration(milliseconds: 50),
+    AutoSaveConfig autoSaveConfig = const AutoSaveConfig(),
+    DateTime Function()? now,
+    this.cheatsEnabled = false,
+  }) : _state = initialState,
+       _tickInterval = tickInterval,
+       _autoSaveConfig = autoSaveConfig,
+       _now = now ?? DateTime.now,
+       _stateController = StreamController<GameState>.broadcast();
+
+  final ProgressService progressService;
+  final SaveManager? saveManager;
+  final Duration _tickInterval;
+  final AutoSaveConfig _autoSaveConfig;
+  final DateTime Function() _now;
+  final StreamController<GameState> _stateController;
+  bool cheatsEnabled;
+
+  Timer? _timer;
+  int? _lastTickMs;
+  int _speedMultiplier = 1;
+
+  GameState get current => _state;
+  Stream<GameState> get stream => _stateController.stream;
+  GameState _state;
+
+  /// 현재 배속 (1x, 2x, 5x)
+  int get speedMultiplier => _speedMultiplier;
+
+  /// 배속 순환: 1 -> 2 -> 5 -> 1
+  void cycleSpeed() {
+    _speedMultiplier = switch (_speedMultiplier) {
+      1 => 2,
+      2 => 5,
+      _ => 1,
+    };
+  }
+
+  void start() {
+    _lastTickMs = _now().millisecondsSinceEpoch;
+    _timer ??= Timer.periodic(_tickInterval, (_) => tickOnce());
+  }
+
+  Future<void> stop({bool saveOnStop = false}) async {
+    _timer?.cancel();
+    _timer = null;
+    if (saveOnStop && _autoSaveConfig.onStop && saveManager != null) {
+      await saveManager!.saveState(_state);
+    }
+  }
+
+  void dispose() {
+    _timer?.cancel();
+    _stateController.close();
+  }
+
+  /// Run one iteration of the loop (used by Timer or manual stepping).
+  GameState tickOnce({int? deltaMillis}) {
+    final baseDelta = deltaMillis ?? _computeDelta();
+    final delta = baseDelta * _speedMultiplier;
+    final result = progressService.tick(_state, delta);
+    _state = result.state;
+    _stateController.add(_state);
+
+    if (saveManager != null && _autoSaveConfig.shouldSave(result)) {
+      saveManager!.saveState(_state);
+    }
+    return _state;
+  }
+
+  /// Replace state (e.g., after loading) and reset timing.
+  void replaceState(GameState newState) {
+    _state = newState;
+    _stateController.add(newState);
+    _lastTickMs = _now().millisecondsSinceEpoch;
+  }
+
+  // Developer-only helpers mirroring original cheat panel actions.
+  void cheatCompleteTask() {
+    if (!cheatsEnabled) return;
+    _state = progressService.forceTaskComplete(_state);
+    _stateController.add(_state);
+  }
+
+  void cheatCompleteQuest() {
+    if (!cheatsEnabled) return;
+    _state = progressService.forceQuestComplete(_state);
+    _stateController.add(_state);
+  }
+
+  void cheatCompletePlot() {
+    if (!cheatsEnabled) return;
+    _state = progressService.forcePlotComplete(_state);
+    _stateController.add(_state);
+  }
+
+  int _computeDelta() {
+    final nowMs = _now().millisecondsSinceEpoch;
+    final last = _lastTickMs;
+    _lastTickMs = nowMs;
+    if (last == null) return 0;
+    final delta = nowMs - last;
+    if (delta < 0) return 0;
+    return delta;
+  }
+}