feat(task-0003): implement boot flow service with menu restart signal and state transitions

- Implement BootFlowService with IStatesController injection and RunFlowAsync logic
- Add Splash → Load → Menu loop with cancellation support in boot flow
- Create IMenuRestartSignal interface for menu restart coordination
- Implement MenuRestartSignal using UniTaskCompletionSource
- Update MenuState to wait for restart signal instead of completing immediately
- Register MenuRestartSignal as singleton in GameLifetimeScope DI container

Выполнена задача TASK-0003 и реализован поток загрузки:
- Реализован BootFlowService с внедрением IStatesController и логикой RunFlowAsync
- Добавлен цикл Splash → Load → Menu с поддержкой отмены в потоке загрузки
- Создан интерфейс IMenuRestartSignal для координации перезапуска меню
- Реализован MenuRestartSignal с использованием UniTaskCompletionSource
- Обновлён MenuState для ожидания сигнала перезапуска вместо немедленного завершения
- Зарегистрирован MenuRestartSignal как синглтон в DI контейнере GameLifetimeScope

Agent/Task/TASK-0003.md

@@ -1,5 +1,9 @@
 # TASK-0003: BootFlowService и запуск сценария
 
+## Статус
+
+Ready
+
 ## Цель
 
 Реализовать внешний flow coordinator, который запускает и управляет сценарием загрузки приложения.

Assets/Scripts/Boot/Composition/GameLifetimeScope.cs

@@ -29,6 +29,9 @@ namespace QuizPleaseTest.Boot.Composition
                 .As<IBootFlowService>()
                 .As<IService>();
 
+            builder.Register<MenuRestartSignal>(Lifetime.Singleton)
+                .As<IMenuRestartSignal>();
+
             builder.Register<BootStatesController>(Lifetime.Singleton)
                 .As<IStatesController<BootStateCode>>()
                 .AsSelf();

Assets/Scripts/Boot/Flow/BootFlowService.cs

@@ -1,19 +1,42 @@
 using System.Threading;
 using Cysharp.Threading.Tasks;
+using QuizPleaseTest.Boot.States;
 using QuizPleaseTest.Common.Services;
+using QuizPleaseTest.Common.StateMachine;
 
 namespace QuizPleaseTest.Boot.Flow
 {
     public class BootFlowService : Service, IBootFlowService
     {
-        public override UniTask InitializeAsync(CancellationToken ct)
+        private readonly IStatesController<BootStateCode> _statesController;
+
+        public BootFlowService(IStatesController<BootStateCode> statesController)
         {
-            return UniTask.CompletedTask;
+            _statesController = statesController;
+        }
+
+        public override async UniTask InitializeAsync(CancellationToken ct)
+        {
+            await RunFlowAsync(ct);
         }
 
         public override UniTask ReleaseAsync(CancellationToken ct)
         {
             return UniTask.CompletedTask;
         }
+
+        private async UniTask RunFlowAsync(CancellationToken ct)
+        {
+            await _statesController.EnterStateAsync(BootStateCode.Splash, ct);
+            await _statesController.EnterStateAsync(BootStateCode.Load, ct);
+
+            while (!ct.IsCancellationRequested)
+            {
+                await _statesController.EnterStateAsync(BootStateCode.Menu, ct);
+                await _statesController.EnterStateAsync(BootStateCode.Load, ct);
+            }
+
+            ct.ThrowIfCancellationRequested();
+        }
     }
 }

Assets/Scripts/Boot/Flow/IMenuRestartSignal.cs

@@ -0,0 +1,11 @@
+using System.Threading;
+using Cysharp.Threading.Tasks;
+
+namespace QuizPleaseTest.Boot.Flow
+{
+    public interface IMenuRestartSignal
+    {
+        UniTask WaitAsync(CancellationToken ct);
+        void RequestRestart();
+    }
+}

Assets/Scripts/Boot/Flow/IMenuRestartSignal.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: a2222222222222222222222222222222
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/Scripts/Boot/Flow/MenuRestartSignal.cs

@@ -0,0 +1,23 @@
+using System.Threading;
+using Cysharp.Threading.Tasks;
+
+namespace QuizPleaseTest.Boot.Flow
+{
+    public class MenuRestartSignal : IMenuRestartSignal
+    {
+        private UniTaskCompletionSource _restartCompletionSource;
+
+        public UniTask WaitAsync(CancellationToken ct)
+        {
+            ct.ThrowIfCancellationRequested();
+
+            _restartCompletionSource = new UniTaskCompletionSource();
+            return _restartCompletionSource.Task.AttachExternalCancellation(ct);
+        }
+
+        public void RequestRestart()
+        {
+            _restartCompletionSource?.TrySetResult();
+        }
+    }
+}

Assets/Scripts/Boot/Flow/MenuRestartSignal.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: a3333333333333333333333333333333
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/Scripts/Boot/States/MenuState.cs

@@ -1,5 +1,6 @@
 using System.Threading;
 using Cysharp.Threading.Tasks;
+using QuizPleaseTest.Boot.Flow;
 using QuizPleaseTest.Boot.UI;
 using QuizPleaseTest.Common.StateMachine;
 
@@ -8,16 +9,18 @@ namespace QuizPleaseTest.Boot.States
     public class MenuState : IState
     {
         private readonly MenuUIView _view;
+        private readonly IMenuRestartSignal _restartSignal;
 
-        public MenuState(MenuUIView view)
+        public MenuState(MenuUIView view, IMenuRestartSignal restartSignal)
         {
             _view = view;
+            _restartSignal = restartSignal;
         }
 
-        public UniTask EnterAsync(CancellationToken ct)
+        public async UniTask EnterAsync(CancellationToken ct)
         {
             _view.Initialize();
-            return UniTask.CompletedTask;
+            await _restartSignal.WaitAsync(ct);
         }
 
         public UniTask ExitAsync(CancellationToken ct)