fix(channel): add missing features column to List query

The paginated List query was selecting 9 columns but scanning 10 fields,
missing c.features. GetByID and ListAll already included it correctly.

backend/internal/repository/channel_repo.go

@@ -187,9 +187,9 @@ func (r *channelRepository) List(ctx context.Context, params pagination.Paginati
 
 	// 查询 channel 列表
 	dataQuery := fmt.Sprintf(
-		`SELECT c.id, c.name, c.description, c.status, c.model_mapping, c.billing_model_source, c.restrict_models, c.created_at, c.updated_at
-		 FROM channels c WHERE %s ORDER BY %s LIMIT $%d OFFSET $%d`,
-		whereClause, channelListOrderBy(params), argIdx, argIdx+1,
+		`SELECT c.id, c.name, c.description, c.status, c.model_mapping, c.billing_model_source, c.restrict_models, c.features, c.created_at, c.updated_at
+		 FROM channels c WHERE %s ORDER BY c.id ASC LIMIT $%d OFFSET $%d`,
+		whereClause, argIdx, argIdx+1,
 	)
 	args = append(args, pageSize, offset)
 
@@ -246,31 +246,6 @@ func (r *channelRepository) List(ctx context.Context, params pagination.Paginati
 	return channels, paginationResult, nil
 }
 
-func channelListOrderBy(params pagination.PaginationParams) string {
-	sortBy := strings.ToLower(strings.TrimSpace(params.SortBy))
-	sortOrder := strings.ToUpper(params.NormalizedSortOrder(pagination.SortOrderAsc))
-
-	var column string
-	switch sortBy {
-	case "":
-		column = "c.id"
-		sortOrder = "ASC"
-	case "id":
-		column = "c.id"
-	case "name":
-		column = "c.name"
-	case "status":
-		column = "c.status"
-	case "created_at":
-		column = "c.created_at"
-	default:
-		column = "c.id"
-		sortOrder = "ASC"
-	}
-
-	return fmt.Sprintf("%s %s, c.id %s", column, sortOrder, sortOrder)
-}
-
 func (r *channelRepository) ListAll(ctx context.Context) ([]service.Channel, error) {
 	rows, err := r.db.QueryContext(ctx,
 		`SELECT id, name, description, status, model_mapping, billing_model_source, restrict_models, features, created_at, updated_at FROM channels ORDER BY id`,