feat: 글 상세 페이지에 대한 디자인 시스템 적용

[MTtankkeo]

작업 내용

글 상세 페이지 전반에 GDS 기반 디자인 시스템을 적용했습니다용.

• 게시글 제목, 작성자, 타입 칩, 공유/더보기 액션 UI 개선
• 삭제 확인 UI를 기존 GrimityDialog에서 GdsAlert로 변경
• 게시글 유틸바 및 공통 유틸바 아이콘/메뉴 동작 정리
• 최신 글 영역을 기존 전용 provider에서 게시판 post provider 기반으로 변경
• 댓글 입력 포커스 관련 불필요 상태 제거

피그마 참고

• 모바일: https://www.figma.com/design/BA5LeHKF3saevi3poE85n2/Grimity_APP?node-id=1-230939&m=dev
• 테블릿: https://www.figma.com/design/BA5LeHKF3saevi3poE85n2/Grimity_APP?node-id=1001-267285&m=dev

[gemini-code-assist]

Code Review

This pull request refactors the post detail presentation layer to adopt GDS (Grimity Design System) components, simplifying layout logic, removing custom app bars, and replacing dialogs with standard alerts. Feedback highlights critical issues where unauthenticated users could be incorrectly identified as authors (isMine evaluating to true) when author information is missing in PostContentView, FeedUtilBar, and PostUtilBar. Additionally, the bookmark item in GrimityUtilBar is incorrectly bound to 'like' actions instead of 'save' actions, and PostLatestView contains a Riverpod anti-pattern by using ref.read inside the build method.

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