Consolidate Kreditkarte/PayPal into one "Online-Zahlung" checkout option

Both already route through the same Stripe PaymentIntent
(automatic_payment_methods: enabled — Stripe's own recommended Payment
Element pattern, letting Stripe itself decide which eligible method to
show). Pre-selecting one of two identical-behind-the-scenes rows before
the payment step was redundant friction, not a real choice. Collapses
them into one option with a hint text explaining the actual instrument
is picked on the next screen; Überweisung is unaffected.

Also refines paymentMethodTitle from a neutral "Online-Zahlung"
placeholder (snapshotted at order-creation time, before the customer has
picked an instrument) to the real one Stripe reports, once payment
confirms — carried through to both the stored order and the
sessionStorage snapshot shown on /bestellbestaetigung.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/payload.ts

@@ -621,6 +621,38 @@ export async function getPaymentMethods(): Promise<PaymentMethod[]> {
   }));
 }
 
+export type CheckoutPaymentOption = PaymentMethod & { hint?: string };
+
+// Kreditkarte and PayPal both resolve to `provider: 'stripe'` today, and
+// both end up on the exact same Stripe PaymentIntent
+// (`automatic_payment_methods: { enabled: true }` — Stripe's own
+// recommended Payment Element pattern lets Stripe itself decide which
+// eligible method to show, rather than the older per-method
+// Checkout-Session split). Pre-selecting one of two identical-behind-the-
+// scenes rows before the payment step is therefore no longer a real
+// choice, just redundant friction — so this collapses every active
+// `stripe` row into one "Online-Zahlung" option (representative id =
+// the first such row's, since app/api/checkout/route.ts only branches on
+// `provider`, never on which specific stripe row was picked) with a hint
+// explaining that the actual instrument is chosen on the next screen.
+// `manual` rows (Überweisung) pass through unchanged — one real gateway
+// there, one option, nothing to collapse.
+export function groupPaymentMethodsForCheckout(methods: PaymentMethod[]): CheckoutPaymentOption[] {
+  const manual = methods.filter((m) => m.provider !== "stripe");
+  const stripeMethods = methods.filter((m) => m.provider === "stripe");
+  if (stripeMethods.length === 0) return manual;
+
+  const combinedIcons = Array.from(new Set(stripeMethods.flatMap((m) => m.icons)));
+  const online: CheckoutPaymentOption = {
+    id: stripeMethods[0].id,
+    title: "Online-Zahlung",
+    icons: combinedIcons,
+    provider: "stripe",
+    hint: "Kreditkarte, PayPal & weitere Methoden — die genaue Zahlungsart wählst du im nächsten Schritt.",
+  };
+  return [...manual, online];
+}
+
 export type WerkzeugeCard = {
   id: number;
   title: string;