fix: 修复项目切换时运行时和系统重复初始化问题

packages/editor-app/src/App.tsx

@@ -631,6 +631,13 @@ function App() {
             await pluginLoader.unloadProjectPlugins(pluginManager);
         }
 
+        // 清理场景（会清理所有实体和系统）
+        // Clear scene (clears all entities and systems)
+        const scene = Core.scene;
+        if (scene) {
+            scene.end();
+        }
+
         // 清理模块系统
         const engineService = EngineService.getInstance();
         engineService.clearModuleSystems();

packages/editor-app/src/hooks/useEngine.ts

@@ -14,6 +14,15 @@ import { EditorEngineSync } from '../services/EditorEngineSync';
 let engineInitialized = false;
 let engineInitializing = false;
 
+/**
+ * 重置引擎初始化状态（在项目关闭时调用）
+ * Reset engine initialization state (called when project is closed)
+ */
+export function resetEngineState(): void {
+    engineInitialized = false;
+    engineInitializing = false;
+}
+
 export interface EngineState {
     initialized: boolean;
     running: boolean;

packages/editor-app/src/services/EngineService.ts

@@ -28,6 +28,7 @@ import {
     type GameRuntimeConfig
 } from '@esengine/runtime-core';
 import { getMaterialManager } from '@esengine/material-system';
+import { resetEngineState } from '../hooks/useEngine';
 import { convertFileSrc } from '@tauri-apps/api/core';
 import { IdGenerator } from '../utils/idGenerator';
 import { TauriAssetReader } from './TauriAssetReader';
@@ -245,7 +246,14 @@ export class EngineService {
             ctx.uiInputSystem.unbind?.();
         }
 
+        // 清理 viewport | Clear viewport
+        this.unregisterViewport('editor-viewport');
+
+        // 重置 useEngine 的模块级状态 | Reset useEngine module-level state
+        resetEngineState();
+
         this._modulesInitialized = false;
+        this._initialized = false;
     }
 
     /**