Adds a title_bar.show_worktree_name setting (default: true) that hides
the worktree picker button in the title bar, mirroring how
show_branch_name gates the branch picker. The "/" separator only renders
when both buttons are visible, and the container is omitted entirely
when both are hidden.

The setting is hide-only: it deliberately does not join the
render_project_items gate, so configurations with show_branch_name and
show_project_items both disabled keep hiding the whole group as before.

Requested in discussion
[zed-industries/zed#54902](https://github.com/zed-industries/zed/discussions/54902).

# Objective

The worktree name is always present in the title bar even when unused.
Unlike the branch name it has no dedicated option to disable it.

Requested in discussion
[zed-industries/zed#54902](https://github.com/zed-industries/zed/discussions/54902).

## Solution

Adds a `title_bar.show_worktree_name` setting (default: true) that hides
the worktree picker button in the title bar, mirroring how
show_branch_name gates the branch picker. The "/" separator only renders
when both buttons are visible, and the container is omitted entirely
when both are hidden.

The setting is hide-only: it deliberately does not join the
render_project_items gate, so configurations with show_branch_name and
show_project_items both disabled keep hiding the whole group as before.

## Testing

I tested the setting added by running the application by adding,
removing and toggling the `title_bar.show_worktree_name` setting in the
`settings.json`

## Self-Review Checklist:

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

## Showcase

<img width="1496" height="982" alt="title_bar.show_worktree_name =
false"
src="https://github.com/user-attachments/assets/b2c502de-a8d8-4409-ba04-5ab807c77a8e"
/>

<img width="1496" height="982" alt="title_bar.show_worktree_name = true"
src="https://github.com/user-attachments/assets/6cea7eb5-0e88-454c-9c97-3b4ad62aed51"
/>

---

Release Notes:

- title_bar: Added title_bar.show_worktree_name (default: true) to hide
worktree picker button

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>