added call SendOnCartPurchase

internal/client/callback.go

@@ -65,6 +65,10 @@ func (c *CallbackClient) SendOnSuccess(ctx context.Context, host string, event *
 		return errors.NewWithError(fmt.Errorf("failed to send success callback: %w", err), errors.ErrInternalError)
 	}
 
+	if err := c.SendOnCartPurchase(ctx, host, event); err != nil {
+		return err
+	}
+
 	return nil
 }