fix(lint): restore repository sort helpers

backend/internal/repository/proxy_repo.go

@@ -248,7 +248,7 @@ func proxyListOrder(params pagination.PaginationParams) []func(*entsql.Selector)
 	sortBy := strings.ToLower(strings.TrimSpace(params.SortBy))
 	sortOrder := params.NormalizedSortOrder(pagination.SortOrderDesc)
 
-	field := proxy.FieldID
+	var field string
 	switch sortBy {
 	case "name":
 		field = proxy.FieldName
@@ -258,8 +258,6 @@ func proxyListOrder(params pagination.PaginationParams) []func(*entsql.Selector)
 		field = proxy.FieldStatus
 	case "created_at":
 		field = proxy.FieldCreatedAt
-	case "id", "":
-		field = proxy.FieldID
 	default:
 		field = proxy.FieldID
 	}

backend/internal/repository/redeem_code_repo.go

@@ -146,7 +146,7 @@ func redeemCodeListOrder(params pagination.PaginationParams) []func(*entsql.Sele
 	sortBy := strings.ToLower(strings.TrimSpace(params.SortBy))
 	sortOrder := params.NormalizedSortOrder(pagination.SortOrderDesc)
 
-	field := redeemcode.FieldID
+	var field string
 	switch sortBy {
 	case "type":
 		field = redeemcode.FieldType
@@ -160,8 +160,6 @@ func redeemCodeListOrder(params pagination.PaginationParams) []func(*entsql.Sele
 		field = redeemcode.FieldCreatedAt
 	case "code":
 		field = redeemcode.FieldCode
-	case "id", "":
-		field = redeemcode.FieldID
 	default:
 		field = redeemcode.FieldID
 	}

backend/internal/repository/user_repo.go

@@ -290,14 +290,12 @@ func userListOrder(params pagination.PaginationParams) []func(*entsql.Selector)
 	sortBy := strings.ToLower(strings.TrimSpace(params.SortBy))
 	sortOrder := params.NormalizedSortOrder(pagination.SortOrderDesc)
 
-	field := dbuser.FieldID
+	var field string
 	defaultField := true
 	switch sortBy {
 	case "email":
 		field = dbuser.FieldEmail
 		defaultField = false
-	case "id", "":
-		field = dbuser.FieldID
 	case "username":
 		field = dbuser.FieldUsername
 		defaultField = false