Audit of the POS catalogue against the supplier price lists: broken
supplier names, cost drift over 15%, negative stock, items not
sellable from stock, and SKUs split across two codes for the same
product. Includes the supplier-name backups taken before any mutation.
Follows the existing convention of keeping dated audit output under
reports/.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>