#53609 introduced a regression where Git Graph keybindings could take
precedence over the search bar. As a result, typing characters like `j`
or `k` in the search field could move the table selection instead of
updating the search query.

This PR fixes that regression by scoping Vim table navigation bindings
away from the search bar. It also adds dedicated `tab` and `shift-tab`
handling for Git Graph focus traversal, with the search bar and graph
table participating as separate tab groups.

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [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

Release Notes:

- N/A