fix: resolve Google login hydration mismatch and dynamic env load

frontend/src/app/auth/register/RegisterForm.tsx

@@ -27,6 +27,7 @@ import { apiClient } from '@/lib/apiClient';
 import { useRegister } from './useRegister';
 import { cn } from '@/lib/utils';
 import type { GoogleAuthResponse } from '../login/types';
+import { useGoogleConfig } from '@/providers/ClientGoogleProvider';
 
 function validateEmail(email: string) {
   return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);
@@ -85,7 +86,7 @@ export function RegisterForm() {
   const searchParams = useSearchParams();
   const redirect = searchParams.get('redirect') || '/dashboard';
 
-  const googleClientId = process.env.NEXT_PUBLIC_GOOGLE_CLIENT_ID || '';
+  const { clientId: googleClientId, enabled: googleEnabled } = useGoogleConfig();
 
   const nameError = touched.name && name.length > 0 && name.length < 2
     ? t('register.name.error')
@@ -179,7 +180,7 @@ export function RegisterForm() {
       </CardHeader>
 
       <CardContent className="space-y-5">
-        {googleClientId && (
+        {googleEnabled && googleClientId && (
           <>
             <div className="flex justify-center">
               {googleLoading ? (