deploy arrproxy (oauth2-gated *arr proxy + per-user API keys)

Adds the arrproxy front door to the arrstack app: the external, oauth-gated
entry to sonarr/radarr/prowlarr with per-user API-key brokering, wired to match
the arrproxy v0.1.0 code (ports, routes, identity headers, keys dir).

Topology (apps/base/arrstack/arrproxy):
- oauth2-proxy Deployment/Service is the single front (Authentik OIDC), path-
  routing via --upstreams to arrproxy-ui (/, static SPA) and arrproxy-api
  (/api token API + /<app> proxy). skip-auth-regex ^/[^/]+/api bypasses auth
  only for the *arr proxy API (/sonarr/api...), keeping /api/tokens + /api/me
  and the UI authenticated.
- Identity+groups reach the api via --pass-user-headers (X-Forwarded-*); the api
  reads ARRPROXY_GROUPS_HEADER=X-Forwarded-Groups (set-xauthrequest is
  auth_request-response-only and never reaches an upstream).
- oauth2-proxy trusts identity.unkin.net's internal-CA cert via a combine-certs
  initContainer (system roots + vault-ca-cert).
- CNPG token store (arrproxy-db, 2 instances, cephrgw backups); a wave-1 Sync
  hook Job applies the schema (arrproxy-api does not self-migrate).
- VaultStaticSecrets for the seeded ARRPROXY_PEPPER and the oauth-credentials;
  the real *arr keys reuse the existing <app>-apikey Secrets (projected one file
  per app into /etc/arrproxy/keys).
- External Gateway (traefik-external, arrstack.unkin.net, vault-issuer TLS) +
  HTTPRoute to the oauth2-proxy entry.

Also adds the arrstack.unkin.net apex A record (-> external DMZ VIP 198.18.199.0)
to the bind-operator unkin.net zone.

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

@@ -102,3 +102,18 @@ spec:
   values:
     # traefik-internal gateway VIP; the ghp Gateway serves ghp.unkin.net there.
     - 198.18.200.4
+---
+apiVersion: bind.unkin.net/v1alpha1
+kind: DNSRecord
+metadata:
+  name: arrstack-dns-internal
+  namespace: bind-internal
+spec:
+  zoneRef: unkin-net
+  name: arrstack
+  type: A
+  ttl: 600
+  values:
+    # traefik-EXTERNAL (DMZ) gateway VIP; the arrproxy Gateway serves the
+    # arrstack.unkin.net front door (oauth2-proxy) there.
+    - 198.18.199.0