refactor: remove ExternalType from CustomerIdentity and related structures

internal/pkg/enums/customer.go

@@ -6,26 +6,6 @@ func GetCustomerSourceTypeLabel(sourceType ExternalSource) string {
 	return GetExternalSourceLabel(ExternalSource(sourceType))
 }
 
-// ExternalType 客户外部身份类型。
-type ExternalType string
-
-const (
-	ExternalTypeGuest ExternalType = "guest"
-	ExternalTypeUser  ExternalType = "user"
-)
-
-var externalTypeLabelMap = map[ExternalType]string{
-	ExternalTypeGuest: "访客",
-	ExternalTypeUser:  "用户",
-}
-
-func GetExternalTypeLabel(externalType ExternalType) string {
-	if s, ok := externalTypeLabelMap[externalType]; ok {
-		return s
-	}
-	return string(externalType)
-}
-
 // 联系方式类型
 type ContactType string