The Agent Panel already lets users rename Terminal Threads. This adds
the same option to the Threads Sidebar. A rename in either place updates
the other.

<p>
<img width="321" height="89" alt="image"
src="https://github.com/user-attachments/assets/189a8598-f0da-4622-a5b0-b6a18a5750b7"
/>
</p>
<p>
<img width="324" height="77" alt="image"
src="https://github.com/user-attachments/assets/2fc9f7aa-c791-4568-8729-fd3a78322d63"
/>
</p>

Release Notes:

- Added support for renaming Terminal Threads from the Threads Sidebar.