fix: 3차 리뷰 LOW — useCallback, 중복 제거, 접근성 강화

- DownloadSection loadInfo useCallback 래핑
- DownloadAdmin reload 중복 → 단일 load 함수
- LoginPage/RegisterPage 에러 메시지 role="alert"

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/DownloadSection.jsx

@@ -1,4 +1,4 @@
-import { useState, useEffect } from 'react';
+import { useState, useEffect, useCallback } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { useAuth } from '../context/useAuth';
 import { getDownloadInfo } from '../api/download';
@@ -14,13 +14,13 @@ export default function DownloadSection() {
   const { user } = useAuth();
   const navigate = useNavigate();
 
-  const loadInfo = () => {
+  const loadInfo = useCallback(() => {
     setReady(false);
     setLoadError(false);
     getDownloadInfo()
       .then((data) => { setInfo(data); setReady(true); })
       .catch(() => { setLoadError(true); setReady(true); });
-  };
+  }, []);
 
   useEffect(() => { loadInfo(); }, []);
 

src/components/admin/DownloadAdmin.jsx

@@ -1,5 +1,5 @@
 // TODO: Add tests for CRUD operations (load download info, upload launcher, upload game)
-import { useState, useEffect } from 'react';
+import { useState, useEffect, useCallback } from 'react';
 import { getDownloadInfo } from '../../api/download';
 import UploadForm from './UploadForm';
 import './AdminCommon.css';
@@ -9,29 +9,7 @@ export default function DownloadAdmin() {
   const [loading, setLoading] = useState(true);
   const [loadError, setLoadError] = useState('');
 
-  useEffect(() => {
-    getDownloadInfo()
-      .then((data) => {
-        setInfo(data);
-        setLoadError('');
-      })
-      .catch((err) => {
-        console.error('다운로드 정보 로드 실패:', err);
-        setLoadError('배포 정보를 불러올 수 없습니다.');
-      })
-      .finally(() => setLoading(false));
-  }, []);
-
-  if (loading) {
-    return (
-      <div className="admin-section">
-        <h2 className="admin-section-title">게임 배포 관리</h2>
-        <p className="admin-loading">불러오는 중...</p>
-      </div>
-    );
-  }
-
-  const reload = () => {
+  const load = useCallback(() => {
     setLoading(true);
     setLoadError('');
     getDownloadInfo()
@@ -44,14 +22,25 @@ export default function DownloadAdmin() {
         setLoadError('배포 정보를 불러올 수 없습니다.');
       })
       .finally(() => setLoading(false));
-  };
+  }, []);
+
+  useEffect(() => { load(); }, [load]);
+
+  if (loading) {
+    return (
+      <div className="admin-section">
+        <h2 className="admin-section-title">게임 배포 관리</h2>
+        <p className="admin-loading">불러오는 중...</p>
+      </div>
+    );
+  }
 
   if (loadError) {
     return (
       <div className="admin-section">
         <h2 className="admin-section-title">게임 배포 관리</h2>
         <p className="admin-error">{loadError}</p>
-        <button className="btn-admin-secondary" onClick={reload}>다시 시도</button>
+        <button className="btn-admin-secondary" onClick={load}>다시 시도</button>
       </div>
     );
   }

src/pages/LoginPage.jsx

@@ -68,7 +68,7 @@ export default function LoginPage() {
           </div>
 
           {justRegistered && <p className="login-success">회원가입이 완료되었습니다. 로그인해주세요.</p>}
-          {error && <p className="login-error">{error}</p>}
+          {error && <p className="login-error" role="alert">{error}</p>}
 
           <button type="submit" className="btn-login" disabled={loading}>
             {loading ? '로그인 중...' : '로그인'}

src/pages/RegisterPage.jsx

@@ -118,7 +118,7 @@ export default function RegisterPage() {
             />
           </div>
 
-          {error && <p className="login-error">{error}</p>}
+          {error && <p className="login-error" role="alert">{error}</p>}
 
           <button type="submit" className="btn-login" disabled={loading}>
             {loading ? '처리 중...' : '회원가입'}