Add internal mail.unkin.net A record (#540)

Mail clients on the lab network reach Stalwart at mail.unkin.net, served by the stalwart-lb PureLB VIP.

- add an internal unkin.net A record for mail pointing at 198.18.200.11

Requires argocd-apps #539 for the VIP to answer.

Reviewed-on: #540
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

apps/base/bind-internal/authoritative/unkin-net/a/kustomization.yaml

@@ -16,5 +16,6 @@ resources:
   - identity.yaml
   - lb1.yaml
   - logviewer.yaml
+  - mail.yaml
   - vlogs.yaml
   - watchstate.yaml

apps/base/bind-internal/authoritative/unkin-net/a/mail.yaml

@@ -0,0 +1,14 @@
+---
+apiVersion: bind.unkin.net/v1alpha1
+kind: DNSRecord
+metadata:
+  name: mail-dns-internal
+  namespace: bind-internal
+spec:
+  zoneRef: unkin-net
+  name: mail
+  type: A
+  ttl: 600
+  values:
+    # stalwart-lb PureLB VIP (IMAPS, submission, HTTPS).
+    - 198.18.200.11