Function fetch_provision 

pub async fn fetch_provision(
    proxy_url: &str,
    token: &str,
) -> Result<ProvisionDoc, String>

Fetch the provision doc from the reserved /.hackamore/provision path on the proxy listener at proxy_url, presenting the token via X-Hackamore-Token. The proxy listener is the only address a sandboxed consumer can reach; the admin listener (which also serves the unauthenticated /mint) stays operator-only.