feat: 优化测量功能架构与引擎组件

- 重构测量激活逻辑，在 Engine 组件中添加统一的 activateMeasure(mode) 方法
- 简化 MeasureDialogManager，移除冗余的 handleMeasureTypeChange 方法
- 添加 EngineManager.activateMeasure 转发方法
- 修复 loadModel 错误，正确调用 Engine 组件方法
- 为 Engine 组件设置固定背景渐变色
- MeasurePanel 初始化时触发 onModeChange 回调
- 添加 MeasureMode 共享类型定义

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/managers/engine-manager.ts

@@ -4,6 +4,7 @@ import type { BimEngine } from '../bim-engine';
 import { RightKeyManager } from './right-key-manager';
 import { infoMenuButton } from '../components/menu/buttons/info';
 import { homeMenuButton } from '../components/menu/buttons/home';
+import type { MeasureMode } from '../types/measure';
 
 /**
  * 3D 引擎管理器
@@ -76,20 +77,20 @@ export class EngineManager extends BimComponent {
     public isInitialized(): boolean {
         return this.engineInstance !== null && this.engineInstance.isInitialized();
     }
-
     /**
      * 加载 3D 模型
      * @param url 模型文件 URL
      * @param options 加载选项（位置、旋转、缩放）
      */
     public loadModel(url: string, options?: ModelLoadOptions): void {
-        if (!this.engineInstance || !this.engineInstance.isInitialized()) {
-            console.error('[EngineManager] 3D Engine not initialized. Please call initialize() first.');
+        if (!this.engineInstance) {
+            console.warn('[EngineManager] 3D Engine not initialized.');
             return;
         }
         this.engineInstance.loadModel(url, options);
     }
 
+
     /**
      * 获取原始 3D 引擎实例
      * 用于直接调用第三方引擎的其他 API
@@ -102,6 +103,50 @@ export class EngineManager extends BimComponent {
         return this.engineInstance.getEngine();
     }
 
+    /**
+     * 回到主视角
+     */
+    public CameraGoHome(): void {
+        if (!this.engineInstance) {
+            console.warn('[EngineManager] 3D Engine not initialized.');
+            return;
+        }
+        this.engineInstance.CameraGoHome();
+    }
+    /**
+     * 激活测量功能
+     * @param mode 测量类型
+     */
+    public activateMeasure(mode: MeasureMode): void {
+        if (!this.engineInstance) {
+            console.warn('[EngineManager] 3D Engine not initialized.');
+            return;
+        }
+        this.engineInstance.activateMeasure(mode);
+    }
+
+    /**
+     * 停用测量功能
+     */
+    public deactivateMeasure(): void {
+        if (!this.engineInstance) {
+            return;
+        }
+        this.engineInstance.deactivateMeasure();
+    }
+
+    /**
+     * 获取当前激活的测量类型
+     */
+    public getCurrentMeasureType(): MeasureMode | null {
+        if (!this.engineInstance) {
+            return null;
+        }
+        return this.engineInstance.getCurrentMeasureType();
+    }
+
+    // ==================== 结束：测量功能方法 ====================
+
     /**
      * 销毁 3D 引擎实例
      */