fix(payments): creditor address per Swedbank TwnNm rule (Validex round 2) (#1508)

A present PstlAdr must carry TwnNm from November 2026 (PFH_222), so
BGNR-to-BGNR payments now carry no creditor address at all (rule 020
requires none there), IBAN-debited payments carry the supplier's town
(snapshotted as payee_city) plus Ctry SE, and the debtor address comes
from company settings, clearing the info-level rule 236 as well.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

types/index.ts

@@ -789,6 +789,8 @@ export interface SupplierPaymentBatchDebtor {
   bic: string
   /** Absent on batches created before the Swedbank MIG fixes (2026-08-10). */
   bankgiro?: string | null
+  /** Company town for Dbtr/PstlAdr; absent on pre-TownName-fix batches. */
+  city?: string | null
 }
 
 export interface SupplierPaymentBatch {
@@ -827,6 +829,8 @@ export interface SupplierPaymentBatchItem {
   payee_clearing: string | null
   payee_account: string | null
   payee_name: string
+  /** Supplier town at creation; feeds Cdtr/PstlAdr/TwnNm on IBAN-debited payments. */
+  payee_city: string | null
   reference_type: SupplierPaymentBatchReferenceType
   reference: string
   created_at: string