feat: Refactor engine structure and add UI customization support

- Refactor  to delegate logic to  and
- Add  for manager classes
- Implement dynamic styling for Toolbar (color config, CSS vars)
- Implement dynamic styling for Dialog (options, CSS vars)
- Add  example
- Add documentation for Toolbar and Dialog
- Update demo to showcase new styling features

src/index.ts

@@ -1,4 +1,10 @@
 import { BimEngine } from './bim-engine';
+
+// 导出 OptBtnGroups 组件，用于工具栏操作
 export { OptBtnGroups } from './toolbar';
+
+// 导出相关类型定义
 export type { OptButton, ButtonGroup, OptBtnGroupsOptions, ClickPayload } from './toolbar/index.type';
-export { BimEngine };
+
+// 导出主引擎类
+export { BimEngine };