Lakehouse Delta tables replace local DuckDB/parquet as the active contract.
New data columns use snake_case; legacy TMDL-bound exceptions remain
documented until migrated.
Shared business invariants are enforced by
utility/src/retail_setup/generation/invariants.py: no sales while closed,
no pre-launch sales, no same-day returns, product lifecycle dates present,
and validated (non-degenerate) profile controls.