cashu.me updates

- show the USD price when paying a Lightning invoice from a BTC mint (price must be turned on in the settings)
- QR code scanner now also supports BIP21 unified addresses
 
THANK YOU FOR THE FEEDBACK 🫡

https://image.nostr.build/92c711a076dca690bf0e28d183fd6e6ac158e94811fb3b2b704a0776ad9679ec.png