- Added `.ipynb` detection and editable-cell conversion utilities, including merge/serialize helpers in `edit/notebook`.
- Rerouted hashline, patch, and replace edit flows, plus read/write paths, through notebook-aware helpers before persistence.
- Removed the dedicated `notebook` tool, its schema flags, renderer, and built-in registration/settings checks.
- Updated notebook read behavior, docs, and tests so `.ipynb` reads return editable `# %%` cells and edits reserialize to JSON.
can1357