feat: 푸터에 GitHub 레포지토리 링크 추가 (#50)

메인 페이지와 about 페이지 푸터에 GitHub 레포 링크를 추가

https://claude.ai/code/session_01FMj7kbG7ZyJ7Pk1rSDTuEd

Co-authored-by: Claude <noreply@anthropic.com>

Author: brody-0125

web/src/app/about/page.tsx

@@ -108,6 +108,7 @@ export default function AboutPage() {
         <footer className="mt-16 pt-8 border-t border-border text-center pb-8">
           <div className="flex justify-center gap-4 text-sm text-text-secondary">
             <span>나들이 프로젝트</span>
+            <a href="https://github.com/brody-0125/nadeuri.today" target="_blank" rel="noopener noreferrer" className="transition-colors hover:text-text-primary">GitHub</a>
           </div>
         </footer>
       </main>

web/src/app/page.tsx

@@ -362,6 +362,7 @@ export default function HomePage() {
           <nav aria-label="푸터 링크" className="mt-3 flex justify-center gap-4 text-xs text-text-secondary">
             <Link href="/about/" className="transition-colors hover:text-status-operating">데이터 출처</Link>
             <Link href="/archive/" className="transition-colors hover:text-status-operating">아카이브</Link>
+            <a href="https://github.com/brody-0125/nadeuri.today" target="_blank" rel="noopener noreferrer" className="transition-colors hover:text-status-operating">GitHub</a>
           </nav>
         </footer>
       )}