Split off from https://github.com/zed-industries/zed/pull/39175

Adds a search bar to the 'profile' panel, so that we can switch profiles
without having to use the mouse or `tab` a few times

![2025-09-30 13 32
55](https://github.com/user-attachments/assets/2fc1f32b-9e25-4059-aae1-d195334a5fdb)

Release Notes:

- agent: Added the ability to search profiles in the agent panel's
profile picker.

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Co-authored-by: Danilo Leal <daniloleal09@gmail.com>