Self-Review Checklist:

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

Corrects the value used for traffic light clearance/padding when
building with the macOS 26 SDK (or later). This was originally fixed in
#45351 but regressed in #48800 where `TRAFFIC_LIGHT_PADDING` was moved
to `ui/src/utils/constants.rs` but the local `build.rs` in `title_bar`
did not apply to the `ui` crate.

Release Notes:

- N/A