feat: NotFound (404) 페이지 추가

- PC/Mobile 404 페이지 구현
- App.jsx에 catch-all 라우트 추가
- pages/common/ 폴더 구조 생성

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/migration.md

@@ -324,8 +324,8 @@ function App() {
 - [x] mobile/Birthday.jsx
 
 ### 페이지 - Common (pages/common/)
-- [ ] pc/NotFound.jsx
-- [ ] mobile/NotFound.jsx
+- [x] pc/NotFound.jsx
+- [x] mobile/NotFound.jsx
 
 ### 페이지 - Admin (pages/admin/) - PC 전용
 - [ ] Login.jsx
@@ -436,7 +436,6 @@ import 'swiper/css';
 ### 미완료 작업
 
 #### 공개 영역
-- [ ] NotFound 페이지 (pc/mobile)
 - [ ] useToast 훅
 
 #### 관리자 영역 (별도 요청 시 진행)

frontend-temp/src/App.jsx

@@ -32,6 +32,7 @@ import {
   PCAlbumGallery,
   MobileAlbumGallery,
 } from '@/pages/album';
+import { PCNotFound, MobileNotFound } from '@/pages/common';
 
 /**
  * PC 환경에서 body에 클래스 추가하는 래퍼
@@ -75,8 +76,8 @@ function App() {
                     <Route path="/album/:name" element={<PCAlbumDetail />} />
                     <Route path="/album/:name/track/:trackTitle" element={<PCTrackDetail />} />
                     <Route path="/album/:name/gallery" element={<PCAlbumGallery />} />
-                    {/* 추가 페이지 */}
-                    {/* <Route path="*" element={<PCNotFound />} /> */}
+                    {/* 404 페이지 */}
+                    <Route path="*" element={<PCNotFound />} />
                   </Routes>
                 </PCLayout>
               }
@@ -146,7 +147,8 @@ function App() {
               </MobileLayout>
             }
           />
-          {/* 추가 페이지 */}
+          {/* 404 페이지 */}
+          <Route path="*" element={<MobileNotFound />} />
         </Routes>
       </MobileView>
     </BrowserRouter>

frontend-temp/src/pages/common/index.js

@@ -0,0 +1,5 @@
+// PC
+export { default as PCNotFound } from './pc/NotFound';
+
+// Mobile
+export { default as MobileNotFound } from './mobile/NotFound';

frontend-temp/src/pages/common/mobile/NotFound.jsx

@@ -0,0 +1,93 @@
+import { motion } from 'framer-motion';
+import { Link } from 'react-router-dom';
+import { Home, ArrowLeft } from 'lucide-react';
+
+/**
+ * Mobile 404 페이지
+ */
+function MobileNotFound() {
+  return (
+    <div className="h-[100dvh] flex items-center justify-center bg-gradient-to-br from-gray-50 to-gray-100 px-6">
+      <div className="text-center">
+        {/* 404 숫자 */}
+        <motion.div
+          initial={{ opacity: 0, scale: 0.5 }}
+          animate={{ opacity: 1, scale: 1 }}
+          transition={{ duration: 0.5, type: 'spring', stiffness: 100 }}
+          className="mb-6"
+        >
+          <h1 className="text-[120px] font-bold leading-none bg-gradient-to-br from-primary to-primary-dark bg-clip-text text-transparent select-none">
+            404
+          </h1>
+        </motion.div>
+
+        {/* 메시지 */}
+        <motion.div
+          initial={{ opacity: 0, y: 20 }}
+          animate={{ opacity: 1, y: 0 }}
+          transition={{ delay: 0.2, duration: 0.5 }}
+          className="mb-6"
+        >
+          <h2 className="text-xl font-bold text-gray-800 mb-2">
+            페이지를 찾을 수 없습니다
+          </h2>
+          <p className="text-sm text-gray-500 leading-relaxed">
+            요청하신 페이지가 존재하지 않거나
+            <br />
+            이동되었을 수 있습니다.
+          </p>
+        </motion.div>
+
+        {/* 장식 요소 */}
+        <motion.div
+          initial={{ opacity: 0 }}
+          animate={{ opacity: 1 }}
+          transition={{ delay: 0.4, duration: 0.5 }}
+          className="flex justify-center gap-2 mb-8"
+        >
+          {[...Array(5)].map((_, i) => (
+            <motion.div
+              key={i}
+              className="w-1.5 h-1.5 rounded-full bg-primary"
+              animate={{
+                y: [0, -6, 0],
+                opacity: [0.3, 1, 0.3],
+              }}
+              transition={{
+                duration: 1.2,
+                repeat: Infinity,
+                delay: i * 0.15,
+                ease: 'easeInOut',
+              }}
+            />
+          ))}
+        </motion.div>
+
+        {/* 버튼들 */}
+        <motion.div
+          initial={{ opacity: 0, y: 20 }}
+          animate={{ opacity: 1, y: 0 }}
+          transition={{ delay: 0.5, duration: 0.5 }}
+          className="flex flex-col gap-3"
+        >
+          <Link
+            to="/"
+            className="flex items-center justify-center gap-2 px-6 py-3.5 bg-gradient-to-r from-primary to-primary-dark text-white rounded-full font-medium shadow-lg shadow-primary/20 active:scale-95 transition-transform"
+          >
+            <Home size={18} />
+            홈으로 가기
+          </Link>
+          <button
+            onClick={() => window.history.back()}
+            className="flex items-center justify-center gap-2 px-6 py-3.5 border-2 border-primary text-primary rounded-full font-medium active:bg-primary/5 transition-colors"
+          >
+            <ArrowLeft size={18} />
+            이전 페이지
+          </button>
+        </motion.div>
+      </div>
+    </div>
+  );
+}
+
+export default MobileNotFound;

frontend-temp/src/pages/common/pc/NotFound.jsx

@@ -0,0 +1,93 @@
+import { motion } from 'framer-motion';
+import { Link } from 'react-router-dom';
+import { Home, ArrowLeft } from 'lucide-react';
+
+/**
+ * PC 404 페이지
+ */
+function NotFound() {
+  return (
+    <div className="flex-1 flex items-center justify-center bg-gradient-to-br from-gray-50 to-gray-100">
+      <div className="text-center px-6">
+        {/* 404 숫자 */}
+        <motion.div
+          initial={{ opacity: 0, scale: 0.5 }}
+          animate={{ opacity: 1, scale: 1 }}
+          transition={{ duration: 0.5, type: 'spring', stiffness: 100 }}
+          className="mb-8"
+        >
+          <h1 className="text-[180px] font-bold leading-none bg-gradient-to-br from-primary to-primary-dark bg-clip-text text-transparent select-none">
+            404
+          </h1>
+        </motion.div>
+
+        {/* 메시지 */}
+        <motion.div
+          initial={{ opacity: 0, y: 20 }}
+          animate={{ opacity: 1, y: 0 }}
+          transition={{ delay: 0.2, duration: 0.5 }}
+          className="mb-8"
+        >
+          <h2 className="text-2xl font-bold text-gray-800 mb-3">
+            페이지를 찾을 수 없습니다
+          </h2>
+          <p className="text-gray-500 leading-relaxed">
+            요청하신 페이지가 존재하지 않거나 이동되었을 수 있습니다.
+            <br />
+            주소를 다시 확인해 주세요.
+          </p>
+        </motion.div>
+
+        {/* 장식 요소 */}
+        <motion.div
+          initial={{ opacity: 0 }}
+          animate={{ opacity: 1 }}
+          transition={{ delay: 0.4, duration: 0.5 }}
+          className="flex justify-center gap-2 mb-10"
+        >
+          {[...Array(5)].map((_, i) => (
+            <motion.div
+              key={i}
+              className="w-2 h-2 rounded-full bg-primary"
+              animate={{
+                y: [0, -8, 0],
+                opacity: [0.3, 1, 0.3],
+              }}
+              transition={{
+                duration: 1.2,
+                repeat: Infinity,
+                delay: i * 0.15,
+                ease: 'easeInOut',
+              }}
+            />
+          ))}
+        </motion.div>
+
+        {/* 버튼들 */}
+        <motion.div
+          initial={{ opacity: 0, y: 20 }}
+          animate={{ opacity: 1, y: 0 }}
+          transition={{ delay: 0.5, duration: 0.5 }}
+          className="flex justify-center gap-4"
+        >
+          <button
+            onClick={() => window.history.back()}
+            className="flex items-center gap-2 px-6 py-3 border-2 border-primary text-primary rounded-full font-medium hover:bg-primary hover:text-white transition-colors duration-200"
+          >
+            <ArrowLeft size={18} />
+            이전 페이지
+          </button>
+          <Link
+            to="/"
+            className="flex items-center gap-2 px-6 py-3 bg-gradient-to-r from-primary to-primary-dark text-white rounded-full font-medium hover:shadow-lg hover:shadow-primary/30 transition-all duration-200"
+          >
+            <Home size={18} />
+            홈으로 가기
+          </Link>
+        </motion.div>
+      </div>
+    </div>
+  );
+}
+
+export default NotFound;