refactor(model): game_state.dart 분할 (SRP 개선)

- Stats, Traits, Inventory, Equipment 등 11개 파일로 분리
- 단일 책임 원칙 적용으로 유지보수성 향상

lib/src/core/model/queue_state.dart

@@ -0,0 +1,37 @@
+import 'dart:collection';
+
+import 'package:asciineverdie/src/core/model/task_info.dart';
+
+/// 큐 종류 (Queue Kind)
+enum QueueKind { task, plot }
+
+/// 큐 엔트리 (Queue Entry)
+class QueueEntry {
+  const QueueEntry({
+    required this.kind,
+    required this.durationMillis,
+    required this.caption,
+    this.taskType = TaskType.neutral,
+  });
+
+  final QueueKind kind;
+  final int durationMillis;
+  final String caption;
+  final TaskType taskType;
+}
+
+/// 큐 상태 (Queue State)
+///
+/// 대기 중인 태스크/플롯 이벤트 큐를 관리
+class QueueState {
+  QueueState({Iterable<QueueEntry>? entries})
+    : entries = Queue<QueueEntry>.from(entries ?? const []);
+
+  final Queue<QueueEntry> entries;
+
+  factory QueueState.empty() => QueueState(entries: const []);
+
+  QueueState copyWith({Iterable<QueueEntry>? entries}) {
+    return QueueState(entries: Queue<QueueEntry>.from(entries ?? this.entries));
+  }
+}