Restore tool cards on thread deserialization (#30053)

Release Notes:

- N/A

---------

Co-authored-by: Julia Ryan <juliaryan3.14@gmail.com>

crates/assistant_tools/src/edit_agent/evals.rs

@@ -895,6 +895,7 @@ fn tool_result(
         tool_name: name.into(),
         is_error: false,
         content: result.into(),
+        output: None,
     })
 }