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/component/is-enabled.md

@@ -0,0 +1,14 @@
+# Component::IsEnabled
+
+检查组件是否启用。
+
+```cpp
+bool IsEnabled() const;
+```
+
+**返回：** `bool` - 如果组件启用则返回 true
+
+## 相关文档
+
+- [Component 总览](component.md)
+- [SetEnabled](set-enabled.md)