feat: add warning alert for past festival pages

Author: modori1208

content/histories/6.mdx

@@ -1,3 +1,8 @@
+---
+title: 2024 HUFS Code Festival
+archived: true
+---
+
 ## 대회 개요
 
 대회 홈페이지([https://codefestival.gdghufs.com](https://codefestival.gdghufs.com)) 통해 참가 신청

content/histories/7.mdx

@@ -1,4 +1,7 @@
-<!-- ============================================ -->
+---
+title: 2025 HUFS Code Festival
+archived: false
+---
 
 ## 개요
 ---

src/app/festival/[id]/page.css.ts

@@ -13,6 +13,14 @@ export const container = style({
   display: 'flex',
 });
 
+export const alert = style({
+  background: '#fff3cd',
+  color: '#856404',
+  padding: `${rem(12)} ${rem(16)}`,
+  borderRadius: rem(8),
+  fontSize: rem(14),
+});
+
 export const article = style({
   width: '100%',
   maxWidth: '100%',

src/app/festival/[id]/page.tsx

@@ -18,7 +18,7 @@ export default async function Page({ params }: PageProps) {
 
   const filePath = path.join(process.cwd(), 'content/histories', `${id}.mdx`);
   const markdownWithMeta = fs.readFileSync(filePath, 'utf-8');
-  const { content } = matter(markdownWithMeta);
+  const { content, data } = matter(markdownWithMeta);
 
   const toc: TOCType[] = [];
 
@@ -47,7 +47,12 @@ export default async function Page({ params }: PageProps) {
     <Layout>
       <BackButton className={styles.backButton} />
       <div className={styles.container}>
-        <article className={styles.article} dangerouslySetInnerHTML={{ __html: code }} />
+        <article className={styles.article}>
+          {data.archived === true && (
+            <div className={styles.alert}>🕓 이 페이지는 이전 행사의 정보를 담고 있습니다.</div>
+          )}
+          <div dangerouslySetInnerHTML={{ __html: code }} />
+        </article>
         <TableOfContents toc={toc} />
       </div>
     </Layout>