Replace HotShop public node with a monero-proxy + random node

[CryptoGrampy]

Public HotShop should point to a public Monero proxy that points to a random public node. This makes for safer zeroconf transactions if the buyer doesn't know the node the HotShop is using.

[CryptoGrampy]

unfortunately, this won't actually solve anything - attacker would simply point at the proxy. a safer way would be to use random web-compatible nodes in the app if user doesn't specify their own