fix(core): ensure Core.destroy() cleans up scene manager

- Add sceneManager.destroy() call in Core.destroy()
- Update lawn-mower-demo submodule

packages/framework/core/src/Core.ts

@@ -742,6 +742,7 @@ export class Core {
         if (!this._instance) return;
 
         this._instance._debugManager?.stop();
+        this._instance._sceneManager.destroy();
         this._instance._serviceContainer.clear();
         Core._logger.info('Core destroyed');
         this._instance = null;