🎨 Palette: [UX improvement] ARIA 라벨 언어 일치화

[seonghobae]

💡 What: <nav> 태그의 aria-label 속성 값을 "Directory listing"에서 "디렉토리 목록"으로 변경했습니다.
🎯 Why: 문서 언어가 한국어(lang="ko")로 설정되어 있음에도 불구하고 ARIA 라벨이 영어로 되어 있어, 스크린 리더 사용 시 한국어 발음 규칙이 영어 단어에 잘못 적용되어 이해하기 어려운 문제가 있었습니다.
📸 Before/After: 시각적인 변화는 없습니다 (스크린 리더 사용자 경험 개선).
♿ Accessibility: 스크린 리더 사용자가 내비게이션 영역의 역할을 정확한 한국어로 안내받을 수 있도록 개선했습니다.

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PR created automatically by Jules for task 2165469600206862119 started by @seonghobae

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