Function build_ws_login_at 

pub fn build_ws_login_at(
    wallet: &str,
    signer: &PrivateKeySigner,
    now_ms: u64,
) -> Result<WsLogin, AuthError>

Builds the WebSocket login body with an injected now_ms reference.

Errors

Returns AuthError::SigningFailed when the underlying secp256k1 signer errors.