Apply payment method normalization consistently across user-facing views

Audited every place Payment.method reaches the UI. The main user
dashboard's per-registration payment list (fed by GET
/api/payments/registration/:id) was still showing the raw gateway
string, since that endpoint is shared with the staff-facing supervisor
payments page and wasn't touched by the earlier /mypayments fix.

Extracted the cash/card/eft/voucher/other normalization (matching
normalizeUserMethod on the backend) into frontend/src/lib/paymentMethod.ts
and applied it to both user-facing payment displays. Staff-facing views
(supervisor payments, at-the-door, reports, cashup) intentionally keep
showing the raw method for reconciliation and were left unchanged.

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

frontend/src/lib/paymentMethod.ts

@@ -0,0 +1,26 @@
+// Payment.method is free-text — online checkouts get tagged with whatever wallet type the
+// gateway reports (apple_pay, google_pay, ...), not just the manual-entry methods below.
+// Mirrors normalizeUserMethod in backend/src/controllers/paymentController.js: card-network
+// wallets count as "card" (same settlement, no separate float); anything else is "other".
+const USER_FACING_METHODS = ["cash", "card", "eft", "voucher"];
+const CARD_ALIASES = ["apple_pay", "google_pay"];
+
+const METHOD_LABELS: Record<string, string> = {
+  cash: "Cash",
+  card: "Card",
+  eft: "EFT",
+  voucher: "Voucher",
+  other: "Other",
+};
+
+export function normalizePaymentMethod(method: string | null | undefined): string {
+  const m = String(method || "").toLowerCase();
+  if (USER_FACING_METHODS.includes(m)) return m;
+  if (CARD_ALIASES.includes(m)) return "card";
+  return "other";
+}
+
+export function formatPaymentMethod(method: string | null | undefined): string {
+  if (!method) return "Payment";
+  return METHOD_LABELS[normalizePaymentMethod(method)];
+}