fix(post) : 사용자 아이디 response 추가

Author: youngseo22

src/main/java/com/example/FixLog/dto/post/PostDto.java

@@ -8,6 +8,7 @@
 @Getter
 @AllArgsConstructor
 public class PostDto {
+    private Long userId;
     private String nickname;
     private String postTitle;
     private String coverImageUrl;

src/main/java/com/example/FixLog/service/PostService.java

@@ -165,6 +165,7 @@ public PostResponseDto viewPost(Long postId){
                 .orElseThrow(() -> new CustomException(ErrorCode.POST_NOT_FOUND));
 
         PostDto postInfo = new PostDto(
+                currentPost.getUserId().getUserId(),
                 currentPost.getUserId().getNickname(),
                 currentPost.getPostTitle(),
                 getDefaultImage(currentPost.getCoverImage()),