fix(invoices): localize payment method (wallet/gateway/mixed) to Persian

The payment method was rendered as the raw enum ("wallet") in the PDF and in the
invoice detail/list views. Map it through the existing methodWallet/methodGateway/
methodMixed dictionary keys everywhere.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/invoice-pdf.ts

@@ -39,6 +39,15 @@ export function buildInvoicePdfData(
   const trDesc = (desc?: string) => (isFa ? translateInvoiceDescription(desc) : desc ?? '');
   const trReason = (reason?: string) => (isFa ? translateInvoiceReason(reason) : reason ?? '-');
 
+  const methodLabel = (m?: string) => {
+    const map: Record<string, string> = {
+      wallet: inv.methodWallet,
+      gateway: inv.methodGateway,
+      mixed: inv.methodMixed,
+    };
+    return m ? map[m] ?? m : '-';
+  };
+
   const cust = customer ?? invoice.user ?? undefined;
   const fullName = [cust?.firstName, cust?.lastName].filter(Boolean).join(' ').trim();
   const phone = cust?.phone || undefined;
@@ -50,7 +59,7 @@ export function buildInvoicePdfData(
   meta.push(
     { label: pdf.application, value: invoice.application?.name || trReason(invoice.reason) },
     { label: pdf.createdAt, value: formatDate(invoice.createdAt) },
-    { label: inv.method, value: invoice.paymentMethod || '-' },
+    { label: inv.method, value: methodLabel(invoice.paymentMethod) },
   );
   if (invoice.paidAt) meta.push({ label: pdf.paidAt, value: formatDate(invoice.paidAt) });
   if (invoice.gatewayTrackingCode) meta.push({ label: inv.tracking, value: invoice.gatewayTrackingCode });