feat: support TON and USDT Jetton payments

- add TON chain, token, RPC, address normalization, and order matching support
- add liteclient scanner with masterchain/shard catch-up and Jetton validation
- add TON manual payment verification and focused tests

src/config/config.go

@@ -352,7 +352,13 @@ func GetRateForCoin(coin string, base string) float64 {
 	if coin == "usdt" && base == "usd" {
 		return 1
 	}
-	return getRateForCoinFromAPI(coin, base)
+	if rate := getRateForCoinFromAPI(coin, base); rate > 0 {
+		return rate
+	}
+	if coin == "ton" {
+		return getRateForCoinFromAPI("toncoin", base)
+	}
+	return 0
 }
 
 func getForcedRateForCoin(coin string, base string) float64 {