Add QR code for invoice payment link on invoice detail page

[MarcusDavidG]

Add a QR code on /invoice/[id] that encodes the invoice URL so payees can scan and open it on mobile. The qrcode.react package is already installed.

[SHEROSE0]

Hello! I have experience in full-stack and blockchain development, and I'd like to take on this issue. I can provide a clean, maintainable solution. Please assign it to me if it's still open.