The smarthost routes all mail through one rspamd: inbound that survived the edge gets the AI (LiteLLM Haiku) pass and is tagged for Stalwart's Junk filing; outbound from the lab and pods is DKIM-signed.
- add rspamd (milter via ClusterIP only), ClamAV and a 3-node sentinel Valkey
- tag inbound (`X-Spam`, `X-Spam-Status`, `X-Spamd-Result`), reject only viruses, tempfail when ClamAV fails
- score inbound against the hop before the edge relays (`external_relay`)
- DKIM-sign and skip GPT only for the smarthost's mynetworks sources
- elect the highest-offset Valkey on full restart; RDB, 384mb `volatile-ttl`
- read a hashed controller password (`password_hash`)
Requires `password_hash` in kv `mail/default/rspamd-controller`.
Reviewed-on: #542
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
