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.

App/editor/Editor.h

@@ -73,6 +73,9 @@ private:
     void DrawMenuBar();       // host 窗口内顶栏
     void DrawDockSpace();     // 全屏 host + dockspace + 默认布局
     void DrawQuitModal();     // 退出确认模态框
+    void DrawSceneModals();   // 保存/加载路径模态框（共用一个路径输入）
+    void DoSaveScene();       // 模态确认动作：目录创建 + 序列化落盘
+    void DoLoadScene();       // 模态确认动作：反序列化 + 选中清空 + 环境恢复 + 回调
 
     EditorContext m_Ctx{};
 
@@ -98,6 +101,11 @@ private:
     // 退出确认链
     bool m_ShowQuitConfirm = false;
     bool m_QuitConfirmed = false;
+
+    // 场景保存/加载（File 菜单 → 路径模态框；无文件对话框库，InputText 手输）
+    bool m_ShowSaveModal = false;
+    bool m_ShowLoadModal = false;
+    char m_ScenePathBuf[256] = "scenes/sandbox.scene";
 };
 
 #endif //HELLOVULKAN_EDITOR_H