fix(database): unblock credit note constraint validation (#1024)

* docs: record legacy credit note migration repair

* fix(database): assert repaired credit note state

---------

Co-authored-by: Jakob Wennberg <jakob.wennberg@gmail.com>

supabase/migrations/20260715181301_reconcile_credit_note_paid_status.sql

@@ -0,0 +1,24 @@
+-- The linked production database contained one legacy credit note in the
+-- ordinary payment lifecycle. It was reconciled before this migration by
+-- linking its existing balanced reversal voucher and normalizing the invoice
+-- metadata. Keep an explicit forward migration that verifies the repaired
+-- invariant before the remaining migration chain proceeds.
+-- pg-test: covered-by lib/invoices/__tests__/credit-note-not-payable.pg.test.ts
+DO $reconcile$
+BEGIN
+  IF EXISTS (
+    SELECT 1
+    FROM public.invoices
+    WHERE credited_invoice_id IS NOT NULL
+      AND status IN ('paid', 'partially_paid')
+  ) THEN
+    RAISE EXCEPTION
+      'Legacy credit notes still use ordinary customer-payment states';
+  END IF;
+END
+$reconcile$;
+
+ALTER TABLE public.invoices
+  VALIDATE CONSTRAINT invoices_credit_note_not_paid;
+
+NOTIFY pgrst, 'reload schema';