agent: Fix panel "go back" button (#31706)

Closes https://github.com/zed-industries/zed/issues/31652.

Release Notes:

- agent: Fixed a bug where the "go back" button wouldn't go back to the
Text Thread after visiting another view from it.
05692e298aDanilo Leal committed on 5/29/2025, 7:00:37 PM· committed by GitHubparentccb049b
1 file changedLine totals unavailable