feat: add homelab-wide Authentik RBAC model and k8s OIDC auth wiring

Adds permissions claim + per-service admin groups in Authentik, scoped
Role/RoleBinding per service, public PKCE kubernetes OAuth2 client, and
kube-apiserver OIDC extraArgs. Also fixes paperless OIDC signup permissions
via adapter override and adds CoreDNS rewrite for authentik.riotpiao.com.

k8s/infra/rbac/kmsvc-operator-role.yaml

@@ -0,0 +1,33 @@
+# Scoped operator access for kmsvc-admins: management-service + its own
+# config only. kmsvc-* CA/cluster/pool secrets and the strimzi-cluster-
+# operator configmap are Strimzi-managed - hand-editing them gets reverted
+# by the operator's reconcile loop or breaks the Kafka cluster. Inert until
+# kube-apiserver's OIDC wiring lands.
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: kmsvc-operator
+  namespace: sqs
+rules:
+  - apiGroups: ["apps"]
+    resources: ["deployments"]
+    resourceNames: ["management-service"]
+    verbs: ["get", "list", "watch", "update", "patch"]
+  - apiGroups: [""]
+    resources: ["configmaps"]
+    resourceNames: ["management-service-config"]
+    verbs: ["get", "list", "watch", "update", "patch"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: kmsvc-admins-binding
+  namespace: sqs
+subjects:
+  - kind: Group
+    name: "oidc:kmsvc-admins"
+    apiGroup: rbac.authorization.k8s.io
+roleRef:
+  kind: Role
+  name: kmsvc-operator
+  apiGroup: rbac.authorization.k8s.io