- Updated the version in `__init__.py` and `version.py` to 4.3.0.
- Introduced `PageNodeManager` to handle the lifecycle of page nodes, including creation, deletion, and management of their state.
- Added API endpoints for listing, creating, retrieving, deleting, starting, stopping, and announcing page nodes.
- Improved the frontend with a new `PageNodesPage` component for managing page nodes and integrated publishing functionality in the `MicronEditorPage`.
