Gutschriften: Auszahlungskonto (Bankkonto des Kunden) fuer Ueberweisungen

Bei Geld-Gutschriften kann die Auszahlung auf ein anderes Konto gehen
als das Vertrags-Abbuchkonto:

- CreditNote.payoutBankCardId + Migration (FK ON DELETE SET NULL, damit
  Loeschen einer Bankkarte die Gutschrift nicht mitreisst).
- Formular: Dropdown mit allen Bankkonten des Kunden (Default =
  Vertrags-Abbuchkonto). getCreditNoteDefaults liefert bankCards +
  contractBankCardId.
- Server prueft, dass die gewaehlte Bankkarte dem Kunden des Vertrags
  gehoert (kein Fremdkonto unterschieben).
- PDF: bei Ueberweisung 'Unsere Bankverbindung' (Absender) + darunter
  'an Bankkonto: <Kunden-IBAN> (<Inhaber>)'. Section-Zeile zeigt das
  Auszahlungskonto.

Lokal verifiziert (Anlage + PDF).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/components/contracts/CreditNotesSection.tsx

@@ -10,7 +10,7 @@ import Input from '../ui/Input';
 import Select from '../ui/Select';
 import Badge from '../ui/Badge';
 import { creditNoteApi } from '../../services/api';
-import type { CreditNote, CreditNoteType, CreditNoteCustomerType, CreditNoteAmountBasis } from '../../types';
+import type { CreditNote, CreditNoteType, CreditNoteCustomerType, CreditNoteAmountBasis, CreditNotePayoutBankCard } from '../../types';
 
 const round2 = (n: number) => Math.round((n + Number.EPSILON) * 100) / 100;
 
@@ -35,6 +35,13 @@ function calcAmounts(amount: number, vatRelevant: boolean, basis: CreditNoteAmou
 
 const todayIso = () => new Date().toISOString().split('T')[0];
 
+interface FormDefaults {
+  customerType: CreditNoteCustomerType;
+  vatRelevant: boolean;
+  bankCards: CreditNotePayoutBankCard[];
+  contractBankCardId: number | null;
+}
+
 interface FormState {
   type: CreditNoteType;
   sachwertDescription: string;
@@ -47,10 +54,11 @@ interface FormState {
   place: string;
   signedAt: string;
   goodsReceived: boolean;
+  payoutBankCardId: string;
   notes: string;
 }
 
-function emptyForm(defaults?: { customerType: CreditNoteCustomerType; vatRelevant: boolean }): FormState {
+function emptyForm(defaults?: FormDefaults): FormState {
   return {
     type: 'GELD',
     sachwertDescription: '',
@@ -63,6 +71,8 @@ function emptyForm(defaults?: { customerType: CreditNoteCustomerType; vatRelevan
     place: '',
     signedAt: '',
     goodsReceived: false,
+    // Vorschlag: das Abbuchkonto des Vertrags (kann umgestellt werden).
+    payoutBankCardId: defaults?.contractBankCardId ? String(defaults.contractBankCardId) : '',
     notes: '',
   };
 }
@@ -81,6 +91,7 @@ function formFromCreditNote(cn: CreditNote): FormState {
     place: cn.place ?? '',
     signedAt: cn.signedAt ? cn.signedAt.split('T')[0] : '',
     goodsReceived: cn.goodsReceived,
+    payoutBankCardId: cn.payoutBankCardId ? String(cn.payoutBankCardId) : '',
     notes: cn.notes ?? '',
   };
 }
@@ -95,11 +106,12 @@ function CreditNoteFormModal({
 }: {
   contractId: number;
   editing: CreditNote | null;
-  defaults?: { customerType: CreditNoteCustomerType; vatRelevant: boolean };
+  defaults?: FormDefaults;
   onClose: () => void;
   onSaved: () => void;
 }) {
   const [form, setForm] = useState<FormState>(editing ? formFromCreditNote(editing) : emptyForm(defaults));
+  const bankCards = defaults?.bankCards ?? [];
   const set = <K extends keyof FormState>(key: K, value: FormState[K]) => setForm((f) => ({ ...f, [key]: value }));
 
   const preview = calcAmounts(parseFloat(form.amount), form.vatRelevant, form.amountBasis, parseFloat(form.vatRate) || 0);
@@ -118,6 +130,7 @@ function CreditNoteFormModal({
         place: form.place || null,
         signedAt: form.signedAt || null,
         goodsReceived: form.type === 'SACHWERT' ? form.goodsReceived : false,
+        payoutBankCardId: form.type === 'GELD' && form.payoutBankCardId ? Number(form.payoutBankCardId) : null,
         notes: form.notes || null,
       };
       return editing ? creditNoteApi.update(editing.id, payload) : creditNoteApi.create(contractId, payload);
@@ -221,6 +234,25 @@ function CreditNoteFormModal({
           </div>
         </div>
 
+        {form.type === 'GELD' && (
+          bankCards.length > 0 ? (
+            <Select
+              label="Auszahlungskonto (Bankkonto des Kunden)"
+              value={form.payoutBankCardId}
+              onChange={(e) => set('payoutBankCardId', e.target.value)}
+              options={bankCards.map((bc) => ({
+                value: String(bc.id),
+                label: `${bc.iban} (${bc.accountHolder})${bc.description ? ` – ${bc.description}` : ''}`,
+              }))}
+              placeholder="Kein Konto angeben"
+            />
+          ) : (
+            <p className="text-xs text-gray-500">
+              Für diesen Kunden sind keine Bankkonten hinterlegt – Auszahlungskonto kann daher nicht gewählt werden.
+            </p>
+          )
+        )}
+
         <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
           <Input
             label="Datum der Gutschrift"
@@ -431,6 +463,12 @@ export default function CreditNotesSection({ contractId, canEdit }: { contractId
                   <div className="text-sm text-gray-600 mt-0.5">{cn.sachwertDescription}</div>
                 )}
                 {cn.notes && <div className="text-xs text-gray-500 mt-0.5 italic">{cn.notes}</div>}
+                {cn.type === 'GELD' && cn.payoutBankCardId && (() => {
+                  const card = defaults?.bankCards.find((bc) => bc.id === cn.payoutBankCardId);
+                  return card ? (
+                    <div className="text-xs text-gray-500 mt-0.5">an Bankkonto: <span className="font-mono">{card.iban}</span> ({card.accountHolder})</div>
+                  ) : null;
+                })()}
                 {cn.type === 'GELD' && (
                   <div className="mt-1">
                     <ReceiptControls cn={cn} canEdit={canEdit} onChanged={refresh} />

frontend/src/types/index.ts

@@ -81,6 +81,7 @@ export interface CreditNote {
   place?: string | null;
   signedAt?: string | null;
   goodsReceived: boolean;
+  payoutBankCardId?: number | null;
   receiptPath?: string | null;
   pdfPath?: string | null;
   notes?: string | null;
@@ -89,10 +90,20 @@ export interface CreditNote {
   updatedAt: string;
 }
 
+export interface CreditNotePayoutBankCard {
+  id: number;
+  iban: string;
+  accountHolder: string;
+  bankName?: string | null;
+  description?: string | null;
+}
+
 export interface CreditNoteDefaults {
   customerType: CreditNoteCustomerType;
   vatRelevant: boolean;
   nextNumber: string;
+  bankCards: CreditNotePayoutBankCard[];
+  contractBankCardId: number | null;
 }
 
 export interface CreditNoteNumberRange {