Harden auth, payments, and frontend against review findings.

Close exploitable gaps in booking/payment flows, enforce token versioning and account checks, gate sensitive payment data, and add middleware plus input validation across admin routes.

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

frontend/next.config.js

@@ -1,28 +1,51 @@
 /** @type {import('next').NextConfig} */
+
+// Backend origin for API/upload proxying. Configurable per environment instead of
+// being hardcoded to localhost.
+const BACKEND_URL = process.env.BACKEND_URL || 'http://localhost:3001';
+
+// Extra image hosts can be allowed via a comma-separated env var (e.g. a CDN).
+const extraImageHosts = (process.env.NEXT_PUBLIC_IMAGE_HOSTS || '')
+  .split(',')
+  .map((h) => h.trim())
+  .filter(Boolean)
+  .map((hostname) => ({ protocol: 'https', hostname }));
+
+const securityHeaders = [
+  { key: 'X-Content-Type-Options', value: 'nosniff' },
+  { key: 'X-Frame-Options', value: 'SAMEORIGIN' },
+  { key: 'Referrer-Policy', value: 'strict-origin-when-cross-origin' },
+  { key: 'X-XSS-Protection', value: '0' },
+  { key: 'Permissions-Policy', value: 'camera=(self), microphone=(), geolocation=()' },
+];
+
 const nextConfig = {
   images: {
-    domains: ['localhost', 'images.unsplash.com'],
+    // Restrict remote image sources to a known allowlist instead of allowing any
+    // https host (which let the Next image optimizer be used as an open proxy).
     remotePatterns: [
-      {
-        protocol: 'https',
-        hostname: '**',
-      },
-      {
-        protocol: 'http',
-        hostname: 'localhost',
-        port: '3001',
-      },
+      { protocol: 'https', hostname: 'images.unsplash.com' },
+      { protocol: 'http', hostname: 'localhost', port: '3001' },
+      ...extraImageHosts,
     ],
   },
+  async headers() {
+    return [
+      {
+        source: '/:path*',
+        headers: securityHeaders,
+      },
+    ];
+  },
   async rewrites() {
     return [
       {
         source: '/api/:path*',
-        destination: 'http://localhost:3001/api/:path*',
+        destination: `${BACKEND_URL}/api/:path*`,
       },
       {
         source: '/uploads/:path*',
-        destination: 'http://localhost:3001/uploads/:path*',
+        destination: `${BACKEND_URL}/uploads/:path*`,
       },
     ];
   },