fix: 封面

@@ -68,7 +68,7 @@ func (l *SystemGetArticleLogic) SystemGetArticle(req *types.SystemArticleGetRequ
 		Tags:         make([]types.ArticleTagItem, 0),
 		TargetUser:   int(article.TargetUser),
 		Videos:       make([]types.Video, 0),
-		Cover:        article.Cover,
+		Cover:        article.GetCover(),
 	}
 
 	for _, val := range article.Videos {

@@ -93,7 +93,7 @@ func (l *SystemSearchArticleLogic) SystemSearchArticle(req *types.SystemArticleS
 				Id:   item.Operator.Id,
 				Name: item.Operator.Name,
 			},
-			Cover: item.Cover,
+			Cover: item.GetCover(),
 		})
 	})
 	return