Refactor monolithic modules and harden booking, email, and auth infrastructure.

Split oversized frontend API client, email service, and admin/booking pages into focused modules while preserving import surfaces, and add Redis-backed queues, stale booking cleanup, stronger auth, and scale deployment configs.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/app/admin/events/[id]/_utils/format.ts

@@ -0,0 +1,20 @@
+// Pure formatting/IO helpers for the admin event detail page.
+
+export function formatCurrency(amount: number, currency: string): string {
+  if (currency === 'PYG') {
+    return `${amount.toLocaleString('es-PY')} PYG`;
+  }
+  return `$${amount.toFixed(2)} ${currency}`;
+}
+
+/** Trigger a browser download for a blob with the given filename. */
+export function downloadBlob(blob: Blob, filename: string): void {
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = filename;
+  document.body.appendChild(a);
+  a.click();
+  document.body.removeChild(a);
+  URL.revokeObjectURL(url);
+}