serialization: scene save/load (Unity-style YAML + UE-style GUID registry)

Engine-layer SceneSerializer (yaml-cpp submodule): entities/components
to versioned YAML, atomic clear-and-rebuild on load with per-entity
fault tolerance, missing-field defaults, unknown-component skip and
UUID dedup. Asset references are {Guid, Path} pairs resolved through
the new AssetManager GUID registry (assets/asset_registry.yaml) with
path fallback; procedural:// pseudo-paths rebuild from parameters.
Editor File menu gets Save/Load Scene modals; app re-resolves stale
entity handles via onSceneLoaded callback.

Engine/include/Engine/Assets/AssetManager.h

@@ -172,14 +172,31 @@ namespace Engine
 
             AssetCache<Model>& Models() { return m_Models; }
 
+            // ---- 资产 GUID 注册表（UE AssetRegistry 模式：中央注册表）----
+            // 磁盘路径资产持久映射 GUID→路径（存 assets/asset_registry.yaml），
+            // 场景文件以 GUID 为主键引用资产——重命名/移动资产不断引用，
+            // Path 仅作人工可读提示与解析兜底。procedural:// 伪路径（参数
+            // 确定性生成，无需稳定身份）不参与
+            // 查询/分配（新路径分配 GUID 并立即持久化，崩溃安全）
+            u64 GetOrCreateGUID(const std::string& path);
+            // GUID → 路径；未登记返回空串
+            std::string ResolveGUID(u64 guid) const;
+
             // 后续扩展点：TextureHandle / MaterialHandle / ShaderHandle
             // 各自一个 AssetCache<T> + 便捷方法，模式与 Model 完全一致。
 
         private:
+            void LoadGUIDRegistry();
+            void SaveGUIDRegistry() const;
+
             IAssetUploader& m_Uploader;
 
             AssetCache<Model> m_Models;
             AssetCache<Cubemap> m_Environments;
+
+            // GUID 注册表（双向）；dirty 即时保存，无析构落盘依赖
+            std::unordered_map<u64, std::string> m_GuidToPath;
+            std::unordered_map<std::string, u64> m_PathToGuid;
         };
     } // namespace Assets
 } // namespace Engine