I want a small, self-contained solution that proves ownership of a Solana wallet by signing a personalised text message. The message must concatenate my chosen username and a unique transaction ID—no images or JSON, just plain text. The wallet owner’s private key has to be used for the signature so anyone can later validate it with the corresponding public key/uniquie text. This is a quick work; need a trustable programmer who can handle the wallet information and help add the required text.