cbfdc0a212
- 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.