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/httproute.yaml

@@ -0,0 +1,58 @@
+---
+# Redirect plain HTTP to HTTPS.
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: arrproxy-http-redirect
+  namespace: arrstack
+  annotations:
+    argocd.argoproj.io/sync-wave: "2"
+spec:
+  hostnames:
+    - arrstack.unkin.net
+  parentRefs:
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: arrproxy
+      sectionName: http
+  rules:
+    - filters:
+        - type: RequestRedirect
+          requestRedirect:
+            scheme: https
+            statusCode: 301
+      matches:
+        - path:
+            type: PathPrefix
+            value: /
+---
+# All HTTPS traffic enters via oauth2-proxy (the arrproxy entry Service), which
+# authenticates and path-routes to arrproxy-ui / arrproxy-api. The UI-vs-api and
+# the /<app>/api oauth-bypass split is done inside oauth2-proxy (upstreams +
+# skip-auth-regex), so a single backend here is sufficient.
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: arrproxy-route
+  namespace: arrstack
+  annotations:
+    argocd.argoproj.io/sync-wave: "2"
+spec:
+  hostnames:
+    - arrstack.unkin.net
+  parentRefs:
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: arrproxy
+      sectionName: https
+  rules:
+    - backendRefs:
+        - group: ""
+          kind: Service
+          name: arrproxy
+          port: 80
+          weight: 1
+      matches:
+        - path:
+            type: PathPrefix
+            value: /