use structured clonning

Author: jankuca

src/notebooks/deepnote/deepnoteCellCopyHandler.ts

@@ -160,7 +160,7 @@ export class DeepnoteCellCopyHandler implements IExtensionSyncActivationService
 
         // Copy all metadata (ID and sortingKey will be generated by onDidChangeNotebookDocument)
         if (cellToCopy.metadata) {
-            const copiedMetadata = { ...cellToCopy.metadata };
+            const copiedMetadata = structuredClone(cellToCopy.metadata);
             newCell.metadata = copiedMetadata;
             logger.debug('DeepnoteCellCopyHandler: Copying cell with metadata preserved');
         }
@@ -171,7 +171,7 @@ export class DeepnoteCellCopyHandler implements IExtensionSyncActivationService
                 (o) =>
                     new NotebookCellOutput(
                         o.items.map((i) => new NotebookCellOutputItem(i.data, i.mime)),
-                        o.metadata ? { ...o.metadata } : undefined
+                        o.metadata ? structuredClone(o.metadata) : undefined
                     )
             );
         }