Function update_client 

pub async fn update_client(
    state: &AppState,
    client_id: ClientId,
    form: ClientForm,
    llm_client: OllamaClient,
    status_tx: UnboundedSender<String>,
) -> Result<UpdateOutcome>

Update a running client by id. Mirror of update_server: unknown id and bad params error cleanly without touching the instance; a remote_addr or startup_params change reconnects, everything else is applied in place.