logging: deploy logviewer v0.1.0 behind oauth2-proxy

The logviewer UI gives browser access to the ClickHouse log store; it is
deployed behind an Authentik-gated oauth2-proxy front so only
akP-logviewer-admin members reach it, at https://logviewer.unkin.net.

- Adds the logviewer Deployment (docker-internal/logviewer:v0.1.0) reading
  ClickHouse via the existing clickhouse-logreader credentials
- Adds an oauth2-proxy front (quay.io v7.15.3) with ak_groups-based
  authorization, mirroring the arrstack pattern
- Syncs kv kubernetes/namespace/logging/default/oauth-credentials into the
  logviewer-oauth-credentials Secret via the existing default VaultAuth
- Adds internal Gateway + HTTPRoutes for logviewer.unkin.net (vault-issuer
  cert, external-dns -> 198.18.200.4, http->https redirect)
- Registers the logviewer directory in the logging kustomization

apps/base/logging/logviewer/kustomization.yaml

@@ -0,0 +1,12 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - vaultstaticsecret.yaml
+  - deployment.yaml
+  - oauth2-proxy-configmap.yaml
+  - oauth2-proxy-deployment.yaml
+  - service.yaml
+  - gateway.yaml
+  - httproute.yaml