This PR adds back the footer with the "Configure" button in the model
selector but only when the seeing it from the Zed agent (or inline
assistant/text threads). I had removed it a while back because seeing
the "Configure" button, which takes you to the agent panel settings
view, when clicking from an external agent didn't make much sense, given
there's nothing model-wise you can configure from Zed (at least yet) for
an external agent.
This also makes the button in the footer a bit nicer by making it full
screen and displaying a keybinding, so that you can easily do the whole
"trigger model selector → go to settings view" all with the keyboard.
<img width="400" height="870" alt="Screenshot 2025-11-21 at 10 38@2x"
src="https://github.com/user-attachments/assets/c14f2acf-b793-4bc1-ac53-8a8a53b219e6"
/>
Release Notes:
- N/A