Open gitignored subdirectories as their own workspace (#60918)

# Objective

Let's git ignored directories be opened as their own project


## Solution

- Add an "ignored dir" carve out when checking project collision

## Testing

- Added tests

## Self-Review Checklist:

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

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Release Notes:

-
e9d6cd2f05Mikayla Maki committed on 7/14/2026, 3:34:30 PM· committed by GitHubparent795c44f
4 files changedLine totals unavailable