Adds payment deep link flow and improves checkout UX

Implements deep link handling for payment confirmation, enabling the app to automatically update order status upon payment completion or failure. Makes shipping method selection optional, removes automatic loading of shipping methods when address changes, and unifies handling of various ID and option fields for compatibility.

Expands translation strings to support new checkout/payment states and updates UI to reflect payment status more clearly on order confirmation.

Improves robustness and flexibility of checkout by handling payment URLs, deep link validation, and asynchronous order/payment flows.

Adds payment deep link flow and improves checkout UX

Implements deep link handling for payment confirmation, enabling automatic order status updates after external payments. Makes shipping method selection optional and removes auto-loading of shipping methods when address changes. Expands translations and updates UI for clearer payment status feedback on order confirmation. Improves checkout robustness by handling payment URLs, deep link validation, and asynchronous order/payment flows. Also unifies handling of ID and option fields for better compatibility.

Relates to improved checkout/payment experience and flexibility.