[refactor] 분실물 게시물 단건 조회 시 학생의 학번도 반환 추가

src/main/java/ussum/homepage/application/post/service/dto/response/postDetail/LostPostDetailResponse.java

@@ -10,12 +10,14 @@
 
 @Getter
 public class LostPostDetailResponse extends PostDetailResDto{
+    private final String studentId;
     private final List<FileResponse> fileResponseList;
 
     @Builder
     private LostPostDetailResponse(Long postId, String categoryName, String authorName, String title, String content, String createdAt, String lastEditedAt, Boolean isAuthor,
-                                   List<FileResponse> fileResponseList, List<String> canAuthority) {
+                                   List<FileResponse> fileResponseList, List<String> canAuthority, String studentId) {
         super(postId, categoryName, authorName, title, content, createdAt, lastEditedAt, isAuthor, canAuthority);
+        this.studentId = studentId;
         this.fileResponseList = fileResponseList;
     }
 
@@ -29,6 +31,7 @@ public static LostPostDetailResponse of(Post post, Boolean isAuthor, User user,
                 .createdAt(post.getCreatedAt())
                 .lastEditedAt(post.getLastEditedAt())
                 .isAuthor(isAuthor)
+                .studentId(user.getStudentId())
                 .fileResponseList(fileResponseList)
                 .build();
     }