Currently, when pressing Shift+Tab to change Zed Agent's profile, the UI
isn't immediately updated. This PR fixes this issue so the `Change
Profile` button updates immediately after pressing Shift+Tab.

The current behavior. Observe that the `Change Profile` button doesn't
update right after Shift+Tab changes the active profile:


https://github.com/user-attachments/assets/fa1e6488-0dc3-4cc9-a4f3-7f62da48cc19

After this fix, the button text is update immediately on profile change:


https://github.com/user-attachments/assets/93261b11-037a-42c9-b1b8-0ca1e1adb851

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Release Notes:

- Fixed Zed Agent profile selector button not visually updating when
cycled with Shift+Tab.

Signed-off-by: k4yt3x <i@k4yt3x.com>