Function send_through_relay 

pub async fn send_through_relay(
    sender: &MailAddress,
    sender_name: &str,
    to: &str,
    message: String,
    message_id: &str,
) -> RelayReceipt

Send message to the Claude session named to, from sender through its relay: start the relay as a hosted runtime when it is not running, queue the send, hand it the send turn through the runtime’s own door, and wait for Claude’s receipt.