8443062b1f
Closes the remaining #310 write paths: credit-note item copies (web, v1, pending-operations) and arcim-migration supplier imports now normalize vat_rate to the decimal-fraction unit before storage, and a NOT VALID CHECK constraint guards every new supplier_invoice_items row. Customer invoice items deliberately stay percent; legacy supplier rows are left untouched so posted-entry reversals reuse the exact original values. Fixes #310 Co-authored-by: Claude Fable 5 <noreply@anthropic.com>