feat: PaymentRequest component — shareable payment link QR code

[gloriaelishahabu]

Overview

Add a PaymentRequest component that generates a shareable Stellar payment URI and QR code. This is a key SDP feature for invoice-style payment collection, especially for the single-use wallet flow.

What needs to be built

• PaymentRequest component in packages/ui/src/components/PaymentRequest/
• Generate a web+stellar:pay?destination=...&amount=...&asset_code=...&memo=... URI
• Render a QR code using a lightweight library (e.g. qrcode.react)
• Copy-to-clipboard button for the URI
• Optional expiry countdown timer (integrates with SingleUseWallet)
• Export from barrel

API shape

<PaymentRequest
  destination="GBZX...WQCA"
  asset={{ code: "USDC", issuer: "GA5Z..." }}
  amount="25.00"
  memo="invoice-1042"
  expiresAt={Date.now() + 1800000}
  onExpire={() => console.log("request expired")}
/>

Generated URI format