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/arrstack/arrproxy/vaultstaticsecret.yaml

@@ -0,0 +1,49 @@
+---
+# Per-deployment token-hash pepper. Seeded (openssl rand) at
+# kv/kubernetes/namespace/arrstack/default/arrproxy-pepper (key: pepper); the
+# default k8s role's templated policy already grants read on
+# kv/data/kubernetes/namespace/{{sa_namespace}}/{{sa_name}}/* for the
+# arrstack/default ServiceAccount, so no terraform-vault change is needed. VSO
+# syncs it into the arrproxy-pepper Secret consumed by arrproxy-api as
+# ARRPROXY_PEPPER.
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
+metadata:
+  name: arrproxy-pepper
+  namespace: arrstack
+  annotations:
+    argocd.argoproj.io/sync-wave: "0"
+spec:
+  destination:
+    create: true
+    name: arrproxy-pepper
+    overwrite: true
+  hmacSecretData: true
+  mount: kv
+  path: kubernetes/namespace/arrstack/default/arrproxy-pepper
+  refreshAfter: 5m
+  type: kv-v2
+  vaultAuthRef: default
+---
+# Authentik OIDC client for the arrstack front door (client_id, client_secret,
+# cookie_secret), created by terraform-authentik at
+# kv/kubernetes/namespace/arrstack/default/oauth-credentials. VSO syncs it into
+# the oauth-credentials Secret consumed by the oauth2-proxy Deployment.
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
+metadata:
+  name: oauth-credentials
+  namespace: arrstack
+  annotations:
+    argocd.argoproj.io/sync-wave: "0"
+spec:
+  destination:
+    create: true
+    name: oauth-credentials
+    overwrite: true
+  hmacSecretData: true
+  mount: kv
+  path: kubernetes/namespace/arrstack/default/oauth-credentials
+  refreshAfter: 5m
+  type: kv-v2
+  vaultAuthRef: default