feat: @提及发送通知 + 通知点击定位高亮

- 新增 NotifyCommentMention 通知类型，归属 mention 分类 TAB
- parseMentions 中向被@用户发送通知（排除自己和重复通知）
- 消息中心 mention 通知可点击跳转至文章页面
- 通过 mention 通知进入时，来源评论置顶并持久半透明高亮
- 普通评论链接保持原有短暂高亮行为不变

internal/service/comment_service.go

@@ -55,15 +55,15 @@ func (s *CommentService) CreateRoot(userID uint, postID uint, body string) (*mod
 	// 文章评论数+1
 	_ = s.repo.IncrCommentsCount(postID)
 
-	// 解析 @ 提及
-	s.parseMentions(comment.ID, body)
+	// 解析 @ 提及 + 发送通知
+	commenterName, _ := s.repo.GetUsernameByID(userID)
+	if commenterName == "" {
+		commenterName = "用户"
+	}
+	s.parseMentions(comment.ID, postID, userID, commenterName, body)
 
 	// 通知文章作者（评论者 ≠ 作者），RelatedID 存 postID 以便消息页生成跳转链接
 	if s.notifier != nil && userID != postAuthorID {
-		commenterName, _ := s.repo.GetUsernameByID(userID)
-		if commenterName == "" {
-			commenterName = "用户"
-		}
 		s.notifier.Create(postAuthorID, model.NotifyComment,
 			"新评论",
 			fmt.Sprintf("%s 评论了你的文章", commenterName),
@@ -103,15 +103,15 @@ func (s *CommentService) CreateReply(userID uint, parentID uint, body string) (*
 	// 文章评论数+1
 	_ = s.repo.IncrCommentsCount(parent.PostID)
 
-	// 解析 @ 提及
-	s.parseMentions(comment.ID, body)
+	// 解析 @ 提及 + 发送通知
+	commenterName, _ := s.repo.GetUsernameByID(userID)
+	if commenterName == "" {
+		commenterName = "用户"
+	}
+	s.parseMentions(comment.ID, parent.PostID, userID, commenterName, body)
 
 	// 通知被回复者（不自己回复自己），RelatedID 存 postID 以便消息页生成跳转链接
 	if s.notifier != nil && parent.UserID != userID {
-		commenterName, _ := s.repo.GetUsernameByID(userID)
-		if commenterName == "" {
-			commenterName = "用户"
-		}
 		s.notifier.Create(parent.UserID, model.NotifyCommentReply,
 			"新回复",
 			fmt.Sprintf("%s 回复了你的评论", commenterName),
@@ -209,10 +209,12 @@ func (s *CommentService) SearchUsers(keyword string, followerUID uint) ([]model.
 	return users, nil
 }
 
-// parseMentions 解析@用户并存储到 comment_mentions 表
-func (s *CommentService) parseMentions(commentID uint, body string) {
+// parseMentions 解析@用户，存储到 comment_mentions 表，并向被@用户发送通知
+func (s *CommentService) parseMentions(commentID uint, postID uint, commenterID uint, commenterName string, body string) {
 	matches := mentionPattern.FindAllStringSubmatch(body, -1)
 	seen := make(map[string]bool)
+	notified := make(map[uint]bool) // 防止重复通知同一用户
+
 	for _, m := range matches {
 		username := m[1]
 		if seen[username] {
@@ -220,12 +222,23 @@ func (s *CommentService) parseMentions(commentID uint, body string) {
 		}
 		seen[username] = true
 		rows, _ := s.repo.SearchUsersByLevel(username, 2, 1, 0)
-		if len(rows) > 0 {
-			_ = s.repo.CreateMention(&model.CommentMention{
-				CommentID:        commentID,
-				UID:              rows[0].UID,
-				OriginalUsername: username,
-			})
+		if len(rows) == 0 {
+			continue
+		}
+		mentionedUID := rows[0].UID
+		_ = s.repo.CreateMention(&model.CommentMention{
+			CommentID:        commentID,
+			UID:              mentionedUID,
+			OriginalUsername: username,
+		})
+
+		// 向被@用户发送通知（排除自己@自己、重复通知）
+		if s.notifier != nil && mentionedUID != commenterID && !notified[mentionedUID] {
+			notified[mentionedUID] = true
+			s.notifier.Create(mentionedUID, model.NotifyCommentMention,
+				"新提及",
+				fmt.Sprintf("%s 在评论中 @ 了你", commenterName),
+				&postID, &commentID)
 		}
 	}
 }