chore: refacto db

backend/gestion/db/db_referral.go

@@ -58,17 +58,3 @@ func (d *Database) ResetClientReferralBalance(username string) error {
 	}
 	return nil
 }
-
-func (d *Database) UseClientReferralBalance(tx *gorm.DB, username string, amount float64) error {
-	if amount <= 0 {
-		return nil
-	}
-	var balance float64
-	if err := tx.Raw(`SELECT referral_balance FROM clients WHERE username = ? FOR UPDATE`, username).Scan(&balance).Error; err != nil {
-		return fmt.Errorf("client non trouvé")
-	}
-	if balance < amount {
-		return fmt.Errorf("solde parrainage insuffisant (disponible: %.2f€)", balance)
-	}
-	return tx.Exec(`UPDATE clients SET referral_balance = referral_balance - ? WHERE username = ?`, amount, username).Error
-}