discount coupon code not reflected if added in payment step

[AAbbadi]

Problem
When a customer applies or removes a discount code during the Payment step of the checkout flow, the Checkout.com payment request does not reflect the updated order total.

This occurs because the payment object/payload is initialized when the user first lands on the payment step. Since applying a coupon in Magento's standard checkout doesn't always trigger a full re-initialization of the payment component's internal data, the extension continues to pass the original amount (pre-discount) to the Checkout.com API. This results in the customer being charged the full price despite a coupon being successfully applied to the Magento quote.

[AAbbadi]

solved this issue in #570