### TL:DR
fix: cannot input space at the beginning of a blank paragraph
> CLOSE BS-3427
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Improved space key handling in the editor: pressing space on an empty AI input now hides the AI panel and inserts a space character back into the editor.
- **Bug Fixes**
- Prevented the AI panel from processing empty input when space is pressed, ensuring smoother user experience.
- **Tests**
- Added an end-to-end test verifying that pressing space on an empty AI input hides the AI panel and inserts a space.
- **Refactor**
- Streamlined event handling logic for space key detection in the editor.
- **Chores**
- Enhanced editor content retrieval to optionally preserve whitespace while removing invisible characters.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
8ea39d5438