Add proxies for some core invoice cryptocurrencies

o Test invoice generation, and default decimals

Author: pjkundert

slip39/defaults.py

@@ -169,3 +169,19 @@
 
 SMTP_TO				= "[email protected]"
 SMTP_FROM			= "[email protected]"
+
+# Invoice options.  Presently, only highly-liquid ERC-20 tokens present in Ethereum AMM (Automatic
+# Market Maker) systems should be used in invoices, since we use 1Inch's "Off-Chain Oracle" smart
+# contract to get current market values.  This prevents us from needing to "trust" anyone to obtain
+# current prices for cryptocurrencies -- if you have access to an Ethereum blockchain (either
+# locally or via an HTTPS API like Alchemy), then we can securely and reliably get current prices.
+# To avoid conflicts, we upper-case symbols, lower-case full names.
+INVOICE_CURRENCY		= "USD"
+INVOICE_PROXIES			= {
+    "USD":		"USDC",
+    "us dollar":	"USDC",
+    "ETH":		"WETH",
+    "ethereum":		"WETH",
+    "BTC":		"WBTC",
+    "bitcoin":		"WBTC",
+}