Move pkg/calc/ to its own repository (19 files, ~4,600 lines): - silo_calc_component.py, sync_engine.py, dialogs.py, push/pull - AI client, completion wizard, settings, sheet format - Addons.xcu, manifest.xml, description.xml, tests Replace docs/CALC_EXTENSION.md with redirect to silo-calc repo and reference to server-side ODS export endpoints. The Calc extension now lives at: https://git.kindred-systems.com/kindred/silo-calc