authentik: serve LDAP via an outpost behind the internal gateway

Adds the LDAP outpost deployment and routes ports 389 and 636 on
gateway-internal to it. 636 is a TLS listener in Terminate mode so
cert-manager renews the LDAPS certificate automatically, and both
listeners forward to the outpost's plaintext 3389.

allowedRoutes.kinds is set explicitly on both listeners: a TCP listener
permits no route kinds by default and a TLS listener defaults to
TLSRoute, so the TCPRoute would not attach otherwise.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

infra/envoy-gateway/kustomization.yaml

@@ -23,6 +23,7 @@ resources:
 
   # Certificates
   - authentik/authentik-certificate.yaml
+  - authentik/authentik-ldap-certificate.yaml
   - argocd/argocd-certificate.yaml
   - bentopdf/bentopdf-certificate.yaml
   - gitea/gitea-certificate.yaml
@@ -70,6 +71,12 @@ patches:
       kind: Gateway
       name: gateway-internal
     path: authentik/authentik-gateway-patch.yaml
+  - target:
+      group: gateway.networking.k8s.io
+      version: v1
+      kind: Gateway
+      name: gateway-internal
+    path: authentik/authentik-ldap-gateway-patch.yaml
   - target:
       group: gateway.networking.k8s.io
       version: v1