支持客服入口按业务场景分流到客服分组

联系客服支持 scene（general/mohong），按用户与场景复用会话；摸大红入口走摸大红分组选人。

backend/internal/modules/supportgroup/dto.go

@@ -5,6 +5,7 @@ import "time"
 const (
 	GroupCodeOwnerOnboarding = "owner_onboarding"
 	GroupCodeRenterHandoff   = "renter_handoff"
+	GroupCodeMohong          = "mohong"
 )
 
 type MemberDTO struct {

backend/internal/modules/supportgroup/repository.go

@@ -225,7 +225,7 @@ func normalizeStatus(status string) string {
 }
 
 func isProtectedCode(code string) bool {
-	return code == GroupCodeOwnerOnboarding || code == GroupCodeRenterHandoff
+	return code == GroupCodeOwnerOnboarding || code == GroupCodeRenterHandoff || code == GroupCodeMohong
 }
 
 func makeCustomCode(name string) string {