Add a notebook-facing facade: CatalogSession/IngestSession + %catalog/%ingest

[oskaresparza]

Summary

• Add a queue-then-commit facade over the developer-oriented catalog/ingestion APIs, aimed at data custodians in JupyterLab — see docs/notebook-facade-for-data-scientists.md for the full design discussion.
• CatalogSession: queue copy/move/tag/untag/set_wiki/delete_wiki/set_meta/create_folder/delete_folder, then commit(retry=True) all-or-nothing, with real rollback via compensating actions (except delete_folder and overwrite=True copies/moves, explicitly flagged as unresolvable rather than silently claimed clean).
• IngestSession: queue FolderIngest runs, commit(retry=True) in order — no rollback by design (documented gap), reports what already landed on a partial failure instead of pretending it can be undone.
• idempotency_key fully encapsulated in both — never a parameter a custodian sees.
• CatalogSession context: a leading . on a path resolves against a "current" prefix kept up to date automatically from ordinary use — no set_context() call needed for normal sequential use.
• %catalog/%ingest (eea_datalakehouse.notebook.magics): thin dispatch onto one session per kernel, friendly error printing instead of tracebacks. Auto-registered by import eea_datalakehouse.notebook — no %load_ext needed, though it still works.
• A Jupyter Comm channel (eea_datalakehouse.catalog_context) lets an integrated frontend push a selected catalog-tree leaf's path into the context invisibly — the receiving half of a future JupyterLab extension integration (the emitting half lives in the separate eeadata/EEALakeHouse repo).
• Adds a notebook extra (ipython) and two worked-example notebooks under docs/notebooks/.

Test plan

• 285 tests passing
• ruff clean on all touched files
• mypy clean on the new session modules (the notebook/ package hits a pre-existing numpy-stub/Python-version mismatch in this environment, confirmed to pre-date this work)

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