Remove test account hint from login page

frontend/src/pages/LoginPage.tsx

@@ -57,8 +57,6 @@ export const LoginPage: React.FC = () => {
         <button className="btn-primary full" type="submit" disabled={busy || !username || !password}>
           {busy ? '로그인 중…' : '로그인'}
         </button>
-
-        <p className="hint">테스트 계정: a(관리자) / s(보안) / h(호스트) · 비밀번호 1</p>
       </form>
     </div>
   );