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/scene/scene-manager/get-active-scene.md

@@ -0,0 +1,29 @@
+# GetActiveScene
+
+Get the currently active scene.
+
+## Syntax
+
+```cpp
+Scene* GetActiveScene() const;
+```
+
+## Returns
+
+Returns a pointer to the currently active `Scene`, or `nullptr` if no scene is active.
+
+## See Also
+
+- [SetActiveScene](set-active-scene)
+
+## Examples
+
+```cpp
+void Example() {
+    SceneManager& manager = SceneManager::Get();
+    Scene* active = manager.GetActiveScene();
+    if (active) {
+        XC_LOG_INFO("Active scene: {}", active->GetName());
+    }
+}
+```