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/transform-component/get-sibling-index.md

@@ -0,0 +1,28 @@
+# GetSiblingIndex
+
+Get the sibling index of this transform among siblings.
+
+## Syntax
+
+```cpp
+int GetSiblingIndex() const;
+```
+
+## Returns
+
+Returns the sibling index of this transform.
+
+## See Also
+
+- [SetSiblingIndex](set-sibling-index)
+- [SetAsFirstSibling](set-as-first-sibling)
+- [SetAsLastSibling](set-as-last-sibling)
+
+## Examples
+
+```cpp
+void Example(TransformComponent* transform) {
+    int index = transform->GetSiblingIndex();
+    XC_LOG_INFO("Sibling index: {}", index);
+}
+```