feat(tools): implement M10 Jupyter notebook support
Add tools-notebook crate with full Jupyter notebook (.ipynb) support:
- Core data structures: Notebook, Cell, NotebookMetadata, Output
- Read/write operations with metadata preservation
- Edit operations: EditCell, AddCell, DeleteCell
- Helper functions: new_code_cell, new_markdown_cell, cell_source_as_string
- Comprehensive test suite: 9 tests covering round-trip, editing, and error handling
- Permission integration: NotebookRead (plan mode), NotebookEdit (acceptedits mode)
Implements M10 from AGENTS.md for LLM-driven notebook editing.
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Co-Authored-By: Claude <noreply@anthropic.com>