feat(repository): enhance repository methods with batch processing and transaction support

- Updated Like and Unlike methods in CommentRepository to use transactions for data consistency.
- Introduced IsLikedBatch method for batch checking if comments are liked, addressing N+1 query issues.
- Enhanced BatchDelete method in PostRepository to perform batch deletions within a single transaction, improving efficiency.
- Added BatchUpdateStatus method for posts to utilize a single SQL update for status changes, reducing database load.
- Implemented BatchUpdateSortOrder in StickerRepository using CASE WHEN for efficient sorting updates.
- Added IsFollowingBatch and IsBlockedBatch methods in UserRepository for batch checking follow and block relationships, optimizing performance.

internal/repository/post_repo.go

@@ -802,30 +802,101 @@ func (r *PostRepository) GetByIDForAdmin(id string) (*model.Post, error) {
 	return &post, nil
 }
 
-// BatchDelete 批量删除帖子
+// BatchDelete 批量删除帖子（使用单次事务批量删除，避免 N+1 问题）
 func (r *PostRepository) BatchDelete(ids []string) ([]string, error) {
-	var failedIDs []string
-
-	for _, id := range ids {
-		if err := r.Delete(id); err != nil {
-			failedIDs = append(failedIDs, id)
-		}
+	if len(ids) == 0 {
+		return nil, nil
 	}
 
-	return failedIDs, nil
+	err := r.db.Transaction(func(tx *gorm.DB) error {
+		// 批量删除帖子图片
+		if err := tx.Where("post_id IN ?", ids).Delete(&model.PostImage{}).Error; err != nil {
+			return err
+		}
+
+		// 批量删除帖子点赞记录
+		if err := tx.Where("post_id IN ?", ids).Delete(&model.PostLike{}).Error; err != nil {
+			return err
+		}
+
+		// 批量删除帖子收藏记录
+		if err := tx.Where("post_id IN ?", ids).Delete(&model.Favorite{}).Error; err != nil {
+			return err
+		}
+
+		// 批量删除评论点赞记录（子查询获取所有评论ID）
+		if err := tx.Where("comment_id IN (SELECT id FROM comments WHERE post_id IN ?)", ids).Delete(&model.CommentLike{}).Error; err != nil {
+			return err
+		}
+
+		// 批量删除帖子评论
+		if err := tx.Where("post_id IN ?", ids).Delete(&model.Comment{}).Error; err != nil {
+			return err
+		}
+
+		// 批量删除投票选项
+		if err := tx.Where("post_id IN ?", ids).Delete(&model.VoteOption{}).Error; err != nil {
+			return err
+		}
+
+		// 批量删除用户投票记录
+		if err := tx.Where("post_id IN ?", ids).Delete(&model.UserVote{}).Error; err != nil {
+			return err
+		}
+
+		// 最后批量删除帖子本身（软删除）
+		return tx.Where("id IN ?", ids).Delete(&model.Post{}).Error
+	})
+
+	if err != nil {
+		return ids, err
+	}
+	return nil, nil
 }
 
-// BatchUpdateStatus 批量更新帖子审核状态
+// BatchUpdateStatus 批量更新帖子审核状态（使用单条 SQL 批量更新，避免 N+1 问题）
 func (r *PostRepository) BatchUpdateStatus(ids []string, status model.PostStatus, reviewedBy string) ([]string, error) {
-	var failedIDs []string
-
-	for _, id := range ids {
-		if err := r.UpdateModerationStatus(id, status, "", reviewedBy); err != nil {
-			failedIDs = append(failedIDs, id)
-		}
+	if len(ids) == 0 {
+		return nil, nil
 	}
 
-	return failedIDs, nil
+	// 使用单条 SQL 批量更新
+	result := r.db.Model(&model.Post{}).
+		Where("id IN ?", ids).
+		Updates(map[string]any{
+			"status":       status,
+			"reviewed_at":  gorm.Expr("CURRENT_TIMESTAMP"),
+			"reviewed_by":  reviewedBy,
+			"reject_reason": "",
+			"updated_at":   gorm.Expr("updated_at"),
+		})
+
+	if result.Error != nil {
+		return ids, result.Error
+	}
+
+	// 返回实际更新的帖子数量
+	if result.RowsAffected < int64(len(ids)) {
+		// 部分帖子可能不存在，查询实际更新的 ID
+		var updatedIDs []string
+		r.db.Model(&model.Post{}).Where("id IN ?", ids).Pluck("id", &updatedIDs)
+
+		// 找出未更新的 ID
+		updatedMap := make(map[string]bool, len(updatedIDs))
+		for _, id := range updatedIDs {
+			updatedMap[id] = true
+		}
+
+		var failedIDs []string
+		for _, id := range ids {
+			if !updatedMap[id] {
+				failedIDs = append(failedIDs, id)
+			}
+		}
+		return failedIDs, nil
+	}
+
+	return nil, nil
 }
 
 // UpdatePinStatus 更新帖子置顶状态