deploy stands up Stalwart 0.16, ihasmail and (for a mail host) Caddy as a
compose project: completes Stalwart's bootstrap over x:Bootstrap, links
ihasmail over the private network, requests certificates for both Caddy
(TLS-ALPN-01) and Stalwart (HTTP-01 through Caddy), makes the auto-ban safe
behind the proxy, and proves the link by signing in through the webmail.
--local gives a loopback-only pair. certs retries Stalwart's certificate;
destroy removes a deployment.
e2e/public.sh runs the whole mail-host path against Pebble with no
internet involved.
