[feature] Create and display unique sigil from hash of url

[CryptoGrampy]

For security, a displaying a unique sigil created from the url hash, etc may be helpful for users to make sure their url hasn't been tampered with. Could be displayed at center of QR on every payment. This could also be a way of ensuring payment is going to the right person- you could print off a copy of the code, and ensure patrons/paymet collectors see the same image

[CryptoGrampy]

Nice potential library for this: https://lnquy065.github.io/react-katar/