feat: add i18n and avatar upload

apps/frontend/src/pages/NotFoundPage.tsx

@@ -1,14 +1,16 @@
 import { Link } from 'react-router-dom';
 import { Button } from '@/components/ui/Button';
+import { useI18n } from '@/i18n/i18n';
 
 export function NotFoundPage() {
+  const { t } = useI18n();
   return (
     <div className="flex min-h-screen items-center justify-center p-6">
       <div className="max-w-md rounded-xl border border-border bg-surface p-8 text-center shadow-card">
         <h1 className="font-display text-4xl">404</h1>
-        <p className="mt-2 text-muted">We couldn't find that page.</p>
+        <p className="mt-2 text-muted">{t('notFound.text')}</p>
         <Link to="/" className="mt-4 inline-block">
-          <Button variant="secondary">Back to home</Button>
+          <Button variant="secondary">{t('common.backHome')}</Button>
         </Link>
       </div>
     </div>