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.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Cargo.toml

@@ -7,6 +7,7 @@ members = [
     "crates/platform/permissions",
     "crates/tools/bash",
     "crates/tools/fs",
+    "crates/tools/notebook",
     "crates/tools/slash",
     "crates/tools/web",
     "crates/integration/mcp-client",