## Objective

Let projects add hidden file patterns without repeating defaults or
patterns inherited from user settings.

Part of
[#64399](https://github.com/zed-industries/zed/discussions/64399).

## Solution

Extend the `"..."` behavior from #62769, #64222, and #64440 to
`hidden_files`. `"..."` includes the resolved inherited list, omitting
it replaces the list, and `[]` clears it. Duplicate entries retain their
first occurrence.

The default remains `["**/.*"]`, and `project_panel.hide_hidden` still
controls visibility.

## Testing

Tested on macOS with settings merge, worktree integration, and Settings
Editor metadata tests.

To check manually, configure different user and project hidden file
patterns and enable `project_panel.hide_hidden`. Include `"..."` to
retain inherited patterns, then repeat without it and with `[]` to
verify replacement and clearing.

## 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 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
- [x] Performance impact has been considered and is acceptable

---

Release Notes:

- Added support for `"..."` in `hidden_files` so project settings can
extend inherited hidden-file patterns.