feat: add prefabs

lightkeeper/include/Lightkeeper.h

@@ -47,6 +47,8 @@ private:
     void saveCurrentScene();
     void loadScene();
     void createEmptyScene();
+    void saveSelectedPrefab();
+    void instantiatePrefab();
     void findPlayer();
     void submitDebugDraws();
     void submitColliderDebugLines();
@@ -62,6 +64,7 @@ private:
 
     char scenePath[512]{"scenes/debug_scene.json"};
     char newSceneName[128]{"EmptyScene"};
+    char prefabPath[512]{"prefabs/selected.prefab"};
     std::string sceneStatus;
     bool renderColliders{false};
     bool render2DShapes{true};