fix: KeyError 'workspace_key' in create_local_workspace_item

Root cause: ws dict from _get_active_workspace doesn't have 'workspace_key' column
           → ws['workspace_key'] → KeyError → 500 on New Page/New Folder

Fix: use ws['name'] instead (the workspace name from workspaces table)

app/routers/dashboard.py

@@ -803,7 +803,7 @@ async def create_local_workspace_item(request: Request):
     explicit_ws_id = body.get("workspace_id")
     ws = _get_active_workspace(request, user_id=_get_user_id(request))
     ws_id = explicit_ws_id or (ws["id"] if ws else None)
-    ws_key = ws["workspace_key"] if ws and not explicit_ws_id else ""
+    ws_key = (ws["name"] if ws else "Workspace") if not explicit_ws_id else ""
     section = 'Workspace' if item_type == 'folder' else 'Private'
     with get_conn() as conn:
         cursor = conn.execute(