<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Undo/redo history management is now centralized in the workspace, providing more consistent and robust undo/redo behavior.
- History update events are emitted at the workspace level, enabling better tracking of changes.
- **Bug Fixes**
- Improved reliability of undo/redo actions by shifting history management from documents to the workspace.
- **Documentation**
- Updated and clarified documentation for history-related APIs, including improved examples and clearer descriptions.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
### TL;DR
Added new commands to retrieve the first and last content blocks in a document.
### What changed?
- Created `getFirstContentBlockCommand` to find the first content block in a document
- Created `getLastContentBlockCommand` to find the last content block in a document
- Added `getFirstNoteBlock` utility function to find the first note block in a document