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/lib/api/client.ts

@@ -0,0 +1,66 @@
+export const API_BASE = process.env.NEXT_PUBLIC_API_URL || '';
+
+export interface ApiError {
+  error: string;
+}
+
+/** Read the stored auth token (browser only). */
+export function getToken(): string | null {
+  return typeof window !== 'undefined' ? localStorage.getItem('spanglish-token') : null;
+}
+
+export async function fetchApi<T>(
+  endpoint: string,
+  options: RequestInit = {}
+): Promise<T> {
+  const token = getToken();
+
+  const headers: HeadersInit = {
+    'Content-Type': 'application/json',
+    ...options.headers,
+  };
+
+  if (token) {
+    (headers as Record<string, string>)['Authorization'] = `Bearer ${token}`;
+  }
+
+  const res = await fetch(`${API_BASE}${endpoint}`, {
+    ...options,
+    headers,
+  });
+
+  if (!res.ok) {
+    const errorData = await res.json().catch(() => ({ error: 'Request failed' }));
+    const errorMessage = typeof errorData.error === 'string'
+      ? errorData.error
+      : (errorData.message || JSON.stringify(errorData) || 'Request failed');
+    throw new Error(errorMessage);
+  }
+
+  return res.json();
+}
+
+/**
+ * Fetch a file download (CSV/blob) with auth, returning the blob and the
+ * filename parsed from the Content-Disposition header.
+ */
+export async function fetchBlob(
+  endpoint: string,
+  fallbackFilename: string
+): Promise<{ blob: Blob; filename: string }> {
+  const token = getToken();
+  const headers: Record<string, string> = {};
+  if (token) headers['Authorization'] = `Bearer ${token}`;
+
+  const res = await fetch(`${API_BASE}${endpoint}`, { headers });
+  if (!res.ok) {
+    const errorData = await res.json().catch(() => ({ error: 'Export failed' }));
+    throw new Error(errorData.error || 'Export failed');
+  }
+
+  const disposition = res.headers.get('Content-Disposition') || '';
+  const filenameMatch = disposition.match(/filename="?([^"]+)"?/);
+  const filename = filenameMatch ? filenameMatch[1] : fallbackFilename;
+  const blob = await res.blob();
+  return { blob, filename };
+}