### Summary

Keep the prompt editor’s max-width centering, but move the footer
controls out of the same flexible wrapper as the full-height editor and
add `min_h_0()` shrink guards so the editor no longer overlaps the
footer in zoomed/full-screen mode.


#### Before
<img width="1624" height="1061" alt="Screenshot 2026-04-07 at 8 39
03 PM"
src="https://github.com/user-attachments/assets/db889fcd-af8a-4297-a1f9-0acb84e6ead3"
/>

#### After
<img width="1624" height="976" alt="Screenshot 2026-04-07 at 9 14 52 PM"
src="https://github.com/user-attachments/assets/ddae7fd4-e720-432d-b84d-45f667aa7dce"
/>

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #ISSUE

Release Notes:

- N/A or Added/Fixed/Improved ...