[FEAT] 서재 책 삭제 응답에 미등록 상태 반환

[kjhyeon0620]

📄 작업 내용 요약

• 서재 책 삭제 응답의 readingStatus를 null 대신 UNREGISTERED로 반환하도록 수정
• 서재 등록/상태 변경 응답은 기존 독서 상태값이 유지되도록 응답 전용 상태 타입 추가

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📎 Issue 번호

• closed [FEAT] 서재 책 삭제 응답의 readingStatus 미등록 상태값 반환 #282

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✅ 작업 목록

• 기능 구현
• 코드 리뷰 반영
• 테스트 코드 작성
• 문서 업데이트

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📝 기타 참고사항

[coderabbitai]

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 51cca850-1ff2-420d-afd0-8fc03f4a2ca9

📥 Commits

Reviewing files that changed from the base of the PR and between 5136a50 and a5b5ebc.

📒 Files selected for processing (5)

• src/main/java/app/nook/library/dto/LibraryViewDto.java
• src/main/java/app/nook/library/dto/ReadingStatusResponse.java
• src/main/java/app/nook/library/service/LibraryCommandService.java
• src/test/java/app/nook/controller/library/LibraryControllerTest.java
• src/test/java/app/nook/library/service/LibraryServiceTest.java

✨ Finishing Touches

🧪 Generate unit tests (beta)

✅ Unit Test PR creation complete.

• Create PR with unit tests
• Commit unit tests in branch feat/#282-library-delete-reading-status

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[JiwonLee42]

Overall Project	67.99%	🍏
Files changed	100%	🍏

File	Coverage
LibraryCommandService.java	94.47%	🍏

[coderabbitai]

✅ Created PR with unit tests: #284