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/src/app/(public)/login/page.tsx

@@ -10,6 +10,7 @@ import Button from '@/components/ui/Button';
 import Input from '@/components/ui/Input';
 import GoogleSignInButton from '@/components/GoogleSignInButton';
 import { authApi } from '@/lib/api';
+import { safeInternalPath } from '@/lib/safeRedirect';
 import toast from 'react-hot-toast';
 
 function LoginContent() {
@@ -25,8 +26,8 @@ function LoginContent() {
     password: '',
   });
 
-  // Check for redirect after login
-  const redirectTo = searchParams.get('redirect') || '/dashboard';
+  // Check for redirect after login (only same-origin relative paths are honoured)
+  const redirectTo = safeInternalPath(searchParams.get('redirect'), '/dashboard');
 
   const handleSubmit = async (e: React.FormEvent) => {
     e.preventDefault();