refactor: 알림 DTO에 카테고리, 썸네일, 알림 메시지 필드 추가

Author: MEOHIN

src/main/java/com/back/domain/notification/dto/NotificationItemDto.java

@@ -2,6 +2,7 @@
 
 import com.back.domain.notification.entity.Notification;
 import com.back.domain.notification.enums.NotificationType;
+import com.back.domain.post.post.entity.PostImage;
 import java.time.LocalDateTime;
 import lombok.Builder;
 import lombok.Getter;
@@ -13,18 +14,29 @@ public class NotificationItemDto {
     private NotificationType type;
     private Long postId;
     private String postTitle;
+    private String postCategoryName;
+    private String postThumbnailUrl;
+    private String message;
     private boolean read;
     private LocalDateTime createdAt;
 
     public static NotificationItemDto from(Notification n) {
+        String categoryName = n.getPost().getCategory() != null ? n.getPost().getCategory().getName() : null;
+        String thumbnailUrl = n.getPost().getImages().stream()
+                .map(PostImage::getUrl)
+                .findFirst()
+                .orElse(null);
+
         return NotificationItemDto.builder()
                 .id(n.getId())
                 .type(n.getType())
                 .postId(n.getPost().getId())
                 .postTitle(n.getPost().getTitle())
+                .postCategoryName(categoryName)
+                .postThumbnailUrl(thumbnailUrl)
+                .message(n.getMessage())
                 .read(n.isRead())
                 .createdAt(n.getCreatedAt())
                 .build();
     }
 }
-