Let authoritative zones accept puppet client updates

Enables per-host RFC2136 updates from puppet (profiles::dns::updater) to
the bind-authoritative zones.

- add client-update BindTSIGKey (operator-generated)
- set dynamicUpdate: true + updateKeyRef: client-update on all 18
  authoritative zones (allow-update { key client-update; })

apps/base/bind-internal/authoritative/tsigkey.yaml

@@ -9,3 +9,16 @@ metadata:
 spec:
   clusterRef: bind-authoritative
   algorithm: hmac-sha256
+---
+# Client-update key: puppet clients (profiles::dns::updater) nsupdate their own
+# records to the authoritative zones with this key. Operator generates the
+# material into Secret client-update-tsig; the same value must reach puppet
+# eyaml (or the planned Vault-sync bridge) for clients to authenticate.
+apiVersion: bind.unkin.net/v1alpha1
+kind: BindTSIGKey
+metadata:
+  name: client-update
+  namespace: bind-internal
+spec:
+  clusterRef: bind-authoritative
+  algorithm: hmac-sha256