This PR adds a "This Window" section to the worktree picker that's
similar to the one that exists in the recent projects modal. This is
particularly helpful when, for a given project group/repository, you
have more than one worktree loaded, allowing you to more easily switch
between them.

<img width="600" alt="Screenshot 2026-06-04 at 12  53@2x"
src="https://github.com/user-attachments/assets/53a8fcdb-9c34-4b2a-b34e-9bdcad6c040e"
/>

Release Notes:

- Improved worktree navigation UX when a given project has more than one
loaded.