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>

engine/src/Scene/Scene.cpp

@@ -79,6 +79,14 @@ GameObject* Scene::Find(const std::string& name) const {
     return nullptr;
 }
 
+GameObject* Scene::FindByID(GameObjectID id) const {
+    auto it = m_gameObjects.find(id);
+    if (it != m_gameObjects.end()) {
+        return it->second.get();
+    }
+    return nullptr;
+}
+
 GameObject* Scene::FindInChildren(GameObject* parent, const std::string& name) const {
     for (size_t i = 0; i < parent->GetChildCount(); ++i) {
         GameObject* child = parent->GetChild(i);