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/oauth2-proxy-deployment.yaml

@@ -0,0 +1,133 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: arrproxy-oauth2
+  namespace: arrstack
+  annotations:
+    argocd.argoproj.io/sync-wave: "2"
+    configmap.reloader.stakater.com/auto: "true"
+    secret.reloader.stakater.com/reload: "oauth-credentials,vault-ca-cert"
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: arrproxy-oauth2
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+    type: RollingUpdate
+  template:
+    metadata:
+      labels:
+        app: arrproxy-oauth2
+    spec:
+      serviceAccountName: default
+      automountServiceAccountToken: false
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65532
+        runAsGroup: 65532
+        fsGroup: 65532
+        seccompProfile:
+          type: RuntimeDefault
+      initContainers:
+        # identity.unkin.net serves a Vault-PKI cert; combine the system roots
+        # with the internal CA so oauth2-proxy's OIDC HTTP client trusts it.
+        - name: combine-certs
+          image: artifactapi.k8s.syd1.au.unkin.net/dockerhub/library/alpine:3
+          imagePullPolicy: IfNotPresent
+          command:
+            - sh
+            - -c
+            - cat /etc/ssl/certs/ca-certificates.crt /custom-ca/ca.crt > /combined-certs/ca-certificates.crt
+          volumeMounts:
+            - name: vault-ca-cert
+              mountPath: /custom-ca
+              readOnly: true
+            - name: combined-certs
+              mountPath: /combined-certs
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop:
+                - ALL
+          resources:
+            requests:
+              cpu: 50m
+              memory: 32Mi
+            limits:
+              cpu: 200m
+              memory: 64Mi
+      containers:
+        - name: oauth2-proxy
+          image: artifactapi.k8s.syd1.au.unkin.net/ghcr/oauth2-proxy/oauth2-proxy:v7.15.3
+          imagePullPolicy: IfNotPresent
+          ports:
+            - containerPort: 4180
+              name: http
+              protocol: TCP
+          envFrom:
+            - configMapRef:
+                name: arrproxy-oauth2-env
+                optional: false
+          env:
+            - name: OAUTH2_PROXY_CLIENT_ID
+              valueFrom:
+                secretKeyRef:
+                  name: oauth-credentials
+                  key: client_id
+            - name: OAUTH2_PROXY_CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: oauth-credentials
+                  key: client_secret
+            - name: OAUTH2_PROXY_COOKIE_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: oauth-credentials
+                  key: cookie_secret
+          volumeMounts:
+            - name: combined-certs
+              mountPath: /etc/ssl/combined
+              readOnly: true
+          livenessProbe:
+            httpGet:
+              path: /ping
+              port: http
+            initialDelaySeconds: 10
+            periodSeconds: 30
+            timeoutSeconds: 5
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /ready
+              port: http
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            timeoutSeconds: 5
+            failureThreshold: 3
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop:
+                - ALL
+          resources:
+            requests:
+              cpu: 50m
+              memory: 64Mi
+            limits:
+              cpu: 500m
+              memory: 256Mi
+      volumes:
+        - name: vault-ca-cert
+          secret:
+            secretName: vault-ca-cert
+            items:
+              - key: ca.crt
+                path: ca.crt
+        - name: combined-certs
+          emptyDir: {}
+      restartPolicy: Always