Generate transaction for Solana wallet-based authentication using transaction signing
Client Key used to uniquely identify the client
"dk_gyh2eqzfkc4mhp5eiahnndkz"
User wallet address
"6CxnSjtasq5Tzwb4b93AhLofXtiDvMpQ2vTkWdSZqTH7"
Transaction generated for signing
Base64-encoded transaction to be signed by the user