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

src/managers/walk-control-manager.ts

@@ -38,12 +38,12 @@ export class WalkControlManager extends BaseManager {
 
         // 打开漫游面板时，默认激活第一人称模式
         console.log('[WalkControl] 打开漫游面板，激活第一人称模式');
-        this.registry.engine3d?.activateFirstPersonMode();
+        this.engineComponent?.activateFirstPersonMode();
 
         this.panel = new WalkControlPanel({
             onPlanViewToggle: (isActive) => {
                 console.log('[WalkControl] 小地图:', isActive);
-                this.registry.engine3d?.toggleMiniMap();
+                this.engineComponent?.toggleMiniMap();
                 this.emit('walk:plan-view-toggle', { isActive });
             },
             onPathModeToggle: (isActive) => {
@@ -66,17 +66,17 @@ export class WalkControlManager extends BaseManager {
             onSpeedChange: (speed) => {
                 console.log('[WalkControl] 速度变化:', speed);
                 const engineSpeed = speed * 0.1;
-                this.registry.engine3d?.setWalkSpeed(engineSpeed);
+                this.engineComponent?.setWalkSpeed(engineSpeed);
                 this.emit('walk:speed-change', { speed });
             },
             onGravityToggle: (enabled) => {
                 console.log('[WalkControl] 重力:', enabled);
-                this.registry.engine3d?.setWalkGravity(enabled);
+                this.engineComponent?.setWalkGravity(enabled);
                 this.emit('walk:gravity-toggle', { enabled });
             },
             onCollisionToggle: (enabled) => {
                 console.log('[WalkControl] 碰撞:', enabled);
-                this.registry.engine3d?.setWalkCollision(enabled);
+                this.engineComponent?.setWalkCollision(enabled);
                 this.emit('walk:collision-toggle', { enabled });
             },
             onCharacterModelChange: (model) => {
@@ -111,7 +111,7 @@ export class WalkControlManager extends BaseManager {
         this.pathManager?.hide();
 
         console.log('[WalkControl] 关闭漫游面板，退出第一人称模式');
-        this.registry.engine3d?.deactivateFirstPersonMode();
+        this.engineComponent?.deactivateFirstPersonMode();
 
         if (this.panel) {
             this.panel.destroy();