fix(config): update error responses for ClientPaymentUpdate.js to match live API
- FeatureDisabled: error.type 'api_error' → 'api', add code HE_00, message → 'Something went wrong'
- InvalidClientSecret: add code IR_09
- WrongCustomerId: add code IR_18
These changes were identified by API Testing Agent re-verification
against the live API during feedback loop iteration 5.
Co-Authored-By: Paperclip <noreply@paperclip.ing>