nwc: Allow payment with another wallet


When the order is in "waiting-payment" status, there should be a "Show Invoice" button. This way, if the wallet connected to NWC doesn't have enough funds or couldn't pay, the user can pay the invoice from another wallet and the order won't be canceled.

<img width="517" height="765" alt="Image" src="https://github.com/user-attachments/assets/c8ebc0c1-2ba2-4d83-9979-ee845c75c677" />

