Add rspamd, ClamAV and sentinel Valkey to the mail namespace (#542)

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>

apps/base/mail/kustomization.yaml

@@ -3,16 +3,50 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 
 resources:
+  - clamav.yaml
   - cnpg_backup.yaml
   - cnpg_cluster.yaml
   - namespace.yaml
+  - rspamd-deployment.yaml
+  - rspamd-sa-rules.yaml
+  - rspamd-valkey.yaml
+  - rspamd-vault.yaml
   - smarthost-networkpolicy.yaml
   - smarthost-pdb.yaml
   - smarthost-service.yaml
   - smarthost-statefulset.yaml
   - stalwart-blobs-bucket.yaml
+  - vaultauth.yaml
 
 configMapGenerator:
+  - name: rspamd-config
+    namespace: mail
+    options:
+      disableNameSuffixHash: true
+    files:
+      - rspamd/actions.conf
+      - rspamd/antivirus.conf
+      - rspamd/dkim_signing.conf
+      - rspamd/external_relay.conf
+      - rspamd/force_actions.conf
+      - rspamd/gpt.conf
+      - rspamd/greylist.conf
+      - rspamd/history_redis.conf
+      - rspamd/local_networks.map
+      - rspamd/milter_headers.conf
+      - rspamd/options.inc
+      - rspamd/redis.conf
+      - rspamd/settings.conf
+      - rspamd/spamassassin.conf
+      - rspamd/worker-controller.inc
+      - rspamd/worker-normal.inc
+      - rspamd/worker-proxy.inc
+  - name: rspamd-valkey-scripts
+    namespace: mail
+    options:
+      disableNameSuffixHash: true
+    files:
+      - rspamd-valkey/start.sh
   - name: smarthost-config
     namespace: mail
     options: