feat: @搜索优先展示已关注用户，结果限制最多5条

- SearchUsersByLevel SQL新增LEFT JOIN user_follows，按已关注优先+exp降序
- SearchUsers/followerUID参数贯穿repo→service→controller
- 继续输入时前端自动重新搜索新关键词

internal/controller/comment_action_controller.go

@@ -41,7 +41,7 @@ func (ctrl *CommentController) Delete(c *gin.Context) {
 
 // SearchUsers GET /api/users/search?q=keyword
 func (ctrl *CommentController) SearchUsers(c *gin.Context) {
-	_, _, ok := common.GetGinUser(c)
+	uid, _, ok := common.GetGinUser(c)
 	if !ok {
 		common.Error(c, http.StatusUnauthorized, "请先登录")
 		return
@@ -53,7 +53,7 @@ func (ctrl *CommentController) SearchUsers(c *gin.Context) {
 		return
 	}
 
-	users, err := ctrl.commentService.SearchUsers(q)
+	users, err := ctrl.commentService.SearchUsers(q, uid)
 	if err != nil {
 		common.Error(c, http.StatusInternalServerError, "搜索用户失败")
 		return

internal/controller/interfaces.go

@@ -115,7 +115,7 @@ type commentUseCase interface {
 	Delete(commentID uint, requesterID uint, isAdmin bool) error
 	ListRootComments(postID uint, page, pageSize int) ([]model.Comment, int64, error)
 	ListReplies(rootID uint) ([]model.Comment, error)
-	SearchUsers(keyword string) ([]model.UserSearchResult, error)
+	SearchUsers(keyword string, followerUID uint) ([]model.UserSearchResult, error)
 }
 
 // reactionUseCase ReactionController 对 ReactionService 的最小依赖（ISP：4 个方法）

internal/repository/comment_mention_repo.go

@@ -67,7 +67,8 @@ func (r *CommentRepo) LoadMentionsForComments(comments []model.Comment) error {
 }
 
 // SearchUsersByLevel 搜索指定等级及以上用户（用于@艾特），返回 uid/username/avatar/exp
-func (r *CommentRepo) SearchUsersByLevel(keyword string, minLevel int, limit int) ([]struct {
+// followerUID > 0 时按已关注优先排序，其次按exp降序
+func (r *CommentRepo) SearchUsersByLevel(keyword string, minLevel, limit int, followerUID uint) ([]struct {
 	UID      uint
 	Username string
 	Avatar   string
@@ -83,12 +84,17 @@ func (r *CommentRepo) SearchUsersByLevel(keyword string, minLevel int, limit int
 
 	threshold := model.LevelThresholds[minLevel]
 
-	err := r.db.Table("users").
-		Select("id AS uid, username, avatar, exp").
-		Where("username LIKE ? AND exp >= ? AND deleted_at IS NULL", "%"+keyword+"%", threshold).
-		Order("exp DESC").
-		Limit(limit).
-		Find(&list).Error
+	q := r.db.Table("users AS u").
+		Select("u.id AS uid, u.username, u.avatar, u.exp").
+		Where("u.username LIKE ? AND u.exp >= ? AND u.deleted_at IS NULL", "%"+keyword+"%", threshold).
+		Order("u.exp DESC")
+
+	if followerUID > 0 {
+		q = q.Joins("LEFT JOIN user_follows f ON f.followee_id = u.id AND f.follower_id = ?", followerUID).
+			Order("(f.follower_id IS NOT NULL) DESC, u.exp DESC")
+	}
+
+	err := q.Limit(limit).Find(&list).Error
 
 	var res []struct {
 		UID      uint

internal/service/comment_service.go

@@ -190,9 +190,9 @@ func (s *CommentService) ListAllComments(keyword string, showDeleted bool, page,
 	return rows, total, err
 }
 
-// SearchUsers 搜索LV2+用户（用于@艾特悬浮窗）
-func (s *CommentService) SearchUsers(keyword string) ([]model.UserSearchResult, error) {
-	rows, err := s.repo.SearchUsersByLevel(keyword, 2, 10)
+// SearchUsers 搜索LV2+用户（用于@艾特悬浮窗），已关注优先，最多5条
+func (s *CommentService) SearchUsers(keyword string, followerUID uint) ([]model.UserSearchResult, error) {
+	rows, err := s.repo.SearchUsersByLevel(keyword, 2, 5, followerUID)
 	if err != nil {
 		return nil, fmt.Errorf("搜索用户失败: %w", err)
 	}
@@ -219,7 +219,7 @@ func (s *CommentService) parseMentions(commentID uint, body string) {
 			continue
 		}
 		seen[username] = true
-		rows, _ := s.repo.SearchUsersByLevel(username, 2, 1)
+		rows, _ := s.repo.SearchUsersByLevel(username, 2, 1, 0)
 		if len(rows) > 0 {
 			_ = s.repo.CreateMention(&model.CommentMention{
 				CommentID:        commentID,

internal/service/repository.go

@@ -155,7 +155,7 @@ type commentStore interface {
 	CreateMention(mention *model.CommentMention) error
 	FindPostIDByComment(commentID uint) (uint, error)
 	FindPostAuthorID(postID uint) (uint, error)
-	SearchUsersByLevel(keyword string, minLevel, limit int) ([]struct {
+	SearchUsersByLevel(keyword string, minLevel, limit int, followerUID uint) ([]struct {
 		UID      uint
 		Username string
 		Avatar   string