refactor: slim down EngineManager from 861 to 290 lines by removing passthrough proxy pattern

- EngineManager now only exposes public SDK API (initialize, loadModel, pause/resumeRendering, getEngineComponent, destroy)
- Internal managers access Engine component directly via this.engineComponent getter on BaseManager
- Non-manager components use registry.engine3d.getEngineComponent() for direct Engine access
- Replaced getEngine() with onRawEvent()/offRawEvent() for raw engine event access
- Migrated 62 call sites across 13 files (9 managers, 1 panel, 3 toolbar buttons)
- Updated all architecture docs, API docs, and README to reflect new patterns

docs/ENGINNE_3D/API文档.md

@@ -2,6 +2,21 @@
 
 本文档为 BIM Engine SDK 的完整 API 参考，适合大模型阅读和理解引擎的功能结构。
 
+> 2026-03 更新说明（SDK 接入层）
+>
+> 本文档主体描述的是底层 3D 内核与模块能力。SDK 接入层在本次重构后有以下关键变化：
+>
+> 1. `EngineManager` 已收敛为少量公共 API，不再作为全量透传层。
+> 2. SDK 内部 Manager 统一通过 `BaseManager.engineComponent` 直接访问 `Engine` 组件能力。
+> 3. 非 Manager 组件通过 `registry.engine3d?.getEngineComponent()?.xxx()` 访问 `Engine` 组件。
+> 4. `Engine.getEngine()` 已移除，原始事件访问改为 `onRawEvent()/offRawEvent()`。
+>
+> 若你在接入层实现新功能，请优先参考：
+>
+> - `docs/架构设计.md`
+> - `docs/API调用链.md`
+> - `docs/引擎API对接.md`
+
 ## 目录
 
 1. [核心引擎类](#1-核心引擎类)