mediamark: deploy the media marking app

Adds the mediamark app (Go single binary) to the media project: an
oauth2-proxy-fronted service that reads the shared mediastore CephFS tree
and talks to the adult-tier sonarr/radarr through arrproxy's hash routes.

- Add apps/base/mediamark: namespace, VaultAuth, three VaultStaticSecrets,
  static mediastore PV/PVC, the app Deployment, oauth2-proxy
  ConfigMap/Deployment, two Services, and the internal + external
  Gateway/HTTPRoute pairs.
- Run the app as 1000:1000 so it owns files on the shared media tree
  (hardlink/rename safe), with a read-only root filesystem, all caps
  dropped and no service-account token.
- Project the sonarr/radarr API keys as one file per app under
  /etc/mediamark/keys, mirroring arrproxy's keys projection, with reloader
  annotations on both secrets.
- Front both mediamark.unkin.net (traefik-external, reflected LE wildcard)
  and mediamark.k8s.syd1.au.unkin.net (traefik-internal, vault-issuer) with
  one oauth2-proxy using a relative redirect URL, gated on
  akP-mediamark-user and passing X-Forwarded-Groups to the app.
- Append mediamark to the wildcard-unkin-net reflector namespace lists and
  register the app in the media ApplicationSet and AppProject.

argocd/applicationsets/media.yaml

@@ -14,6 +14,7 @@ spec:
       - path: apps/overlays/*/cheeztv
       - path: apps/overlays/*/arrstack
       - path: apps/overlays/*/watchstate
+      - path: apps/overlays/*/mediamark
   template:
     metadata:
       name: 'media-{{path[3]}}'

argocd/projects/media.yaml

@@ -17,6 +17,8 @@ spec:
       server: https://kubernetes.default.svc
     - namespace: 'watchstate'
       server: https://kubernetes.default.svc
+    - namespace: 'mediamark'
+      server: https://kubernetes.default.svc
   clusterResourceWhitelist:
     - group: ''
       kind: Namespace