docs: Add Component, GameObject, TransformComponent and Scene API documentation

- Add Component class documentation with lifecycle methods
- Add GameObject class documentation with component system
- Add TransformComponent documentation with transform methods
- Add Scene class documentation with GameObject management
- Add SceneManager singleton documentation with scene loading
- Update components.md overview with all component classes
- Update main.md navigation with Scene module

docs/api/components/game-object/fixed-update.md

@@ -0,0 +1,14 @@
+# GameObject::FixedUpdate
+
+固定频率更新游戏对象及其所有组件（用于物理）。
+
+```cpp
+void FixedUpdate();
+```
+
+以固定时间间隔调用，适合物理模拟更新。
+
+## 相关文档
+
+- [GameObject 总览](game-object.md)
+- [Update](update.md)