add support for mainnet and custom messages

Author: aosatinsky

.env

@@ -4,4 +4,4 @@ VITE_APP_URL=https://zengo-x.github.io/solana-test-dapp/
 
 VITE_DEFAULT_NETWORK=devnet # or mainnet
 VITE_RPC_URL_DEVNET=https://api.devnet.solana.com
-VITE_RPC_URL_MAINNET=https://api.mainnet-beta.solana.com
+VITE_RPC_URL_MAINNET=https://solana-rpc.publicnode.com