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/measure-dialog-manager.ts

@@ -1,6 +1,6 @@
-import {BimComponent} from '../core/component';
-import {BimEngine} from '../bim-engine';
-import {BimDialog} from "../components/dialog";
+import { BimComponent } from '../core/component';
+import { BimEngine } from '../bim-engine';
+import { BimDialog } from "../components/dialog";
 import { MeasurePanel } from '../components/measure-panel';
 import type { MeasureConfig, MeasureMode, MeasureResult } from '../components/measure-panel/types';
 
@@ -47,12 +47,11 @@ export class MeasureDialogManager extends BimComponent {
 
         // 创建测量面板（只做 UI，不实现真实测量）
         this.panel = new MeasurePanel({
-            defaultMode: 'distance',      // 默认展示前四个，且默认选中“距离”
+            defaultMode: 'distance',      // 默认展示前四个，且默认选中"距离"
             defaultExpanded: false,
             onModeChange: (mode) => {
-                // 这里只做事件/占位：未来可在这里切换引擎内置工具
-                // 本次需求不实现真实测量，因此仅保留回调位置
                 console.log('[MeasureDialogManager] 当前测量方式已切换：', mode);
+                this.engine.engine?.activateMeasure(mode);
             },
             onClearAll: () => {
                 // 预留：未来可清理引擎测量绘制/标注
@@ -90,6 +89,7 @@ export class MeasureDialogManager extends BimComponent {
             },
             onClose: () => {
                 this.engine.toolbar?.setBtnActive('measure', false)
+                this.destroy()
             }
         });
         this.dialog.init();
@@ -183,6 +183,11 @@ export class MeasureDialogManager extends BimComponent {
     }
 
     public destroy(): void {
+        // 停用测量功能
+        if (this.engine.engine) {
+            this.engine.engine.deactivateMeasure();
+        }
+
         // 关闭弹窗
         if (this.dialog) {
             this.dialog.destroy();