<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Added a toggle in the code block toolbar to show or hide line numbers for individual code blocks.
- The display of line numbers now respects both global and per-block settings, allowing more flexible control.
- **Style**
- Updated styles to hide line numbers when disabled via the new toggle option.
- **Tests**
- Added end-to-end tests to verify toggling line numbers visibility and undo/redo behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->