IAV-790 : add referral code creation and error handling (!10) · Requêtes de fusion · iavia / iavia-user-service · GitLab

saoud marouane a demandé de fusionner feature/IAV-790 vers develop jan. 07, 2026

Add createReferralCode method in CreditService
Call createReferralCode during admin creation flow
Add REFERRAL_CODE_CREATION_FAILED error code in AdminErrorCodes
Add CreditServiceErrorCodes enum for credit service exceptions

Closes IAV-790