Fix editor selection system: SelectionManager ID types and Scene lookup

- SelectionManager now implements ISelectionManager interface with uint64_t IDs
- Remove SelectionManager/SceneManager circular dependency via EventBus
- Add Scene::FindByID() for proper ID-based entity lookup
- SceneManager::GetEntity() now uses FindByID instead of name-based Find
- Fix editor CMakeLists.txt XCEngine.lib path
- EventBus now thread-safe with shared_mutex

engine/include/XCEngine/Scene/Scene.h

@@ -30,6 +30,7 @@ public:
     void DestroyGameObject(GameObject* gameObject);
 
     GameObject* Find(const std::string& name) const;
+    GameObject* FindByID(GameObjectID id) const;
     GameObject* FindGameObjectWithTag(const std::string& tag) const;
     
     template<typename T>