Adds a dylint library under tooling/lints that flags Zed-specific
anti-patterns:
* shared_string_from_str_literal,
* async_block_without_await,
* entity_update_in_render,
* notify_in_render,
* owned_string_into_shared,
* len_in_loop_condition, and
* blocking_io_on_foreground.
Includes UI tests, a single-lint helper, and workspace.metadata.dylint
registration so cargo dylint --all discovers it. The library pins its
own nightly toolchain (kept out of the main workspace) and tracks dylint
6.
Release Notes:
- N/A
Self-Review Checklist:
- [ ] I've reviewed my own diff for quality, security, and reliability
- [ ] Unsafe blocks (if any) have justifying comments
- [ ] 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
- [ ] Performance impact has been considered and is acceptable
Closes #ISSUE
Release Notes:
- N/A or Added/Fixed/Improved ...
