feat(rbac): per-namespace-owner dashboard SA + long-lived token

Pragmatic dashboard access while OIDC SSO is blocked: each namespace-owner
(from k8s_users) gets a ServiceAccount scoped to admin on their namespace(s)
+ cluster read-only, plus a long-lived token to paste into the dashboard
'Token' login. Real per-namespace isolation, no apiserver-OIDC dependency.
Verified: vabbit81 SA = admin in vabbit81, read-only elsewhere, no cross-ns write.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

stacks/rbac/modules/rbac/dashboard-sa.tf

@@ -0,0 +1,81 @@
+# Per-namespace-owner ServiceAccount + long-lived token for Kubernetes Dashboard
+# token-paste access.
+#
+# WHY: seamless OIDC SSO into the dashboard is blocked — the apiserver currently
+# rejects all Authentik OIDC tokens (see docs/plans/2026-06-04-k8s-dashboard-sso-design.md
+# §12). Until that's solved, each namespace-owner gets a ServiceAccount scoped to
+# `admin` on their namespace(s) + cluster read-only, and a long-lived token they
+# paste into the dashboard "Token" login. Real per-namespace isolation, no OIDC
+# dependency. Rotate a token by deleting+recreating its `dashboard-<user>-token`
+# Secret. Retrieve with:
+#   kubectl -n <ns> get secret dashboard-<user>-token -o jsonpath='{.data.token}' | base64 -d
+#
+# Driven by the same `local.namespace_owner_pairs` as the OIDC bindings, so every
+# namespace-owner in k8s_users automatically gets one.
+
+resource "kubernetes_service_account" "dashboard_owner" {
+  for_each = nonsensitive({ for pair in local.namespace_owner_pairs : "${pair.user_key}-${pair.namespace}" => pair })
+
+  metadata {
+    name      = "dashboard-${each.value.user_key}"
+    namespace = each.value.namespace
+  }
+}
+
+# Full admin within the owner's namespace (same scope as their OIDC RoleBinding).
+resource "kubernetes_role_binding" "dashboard_owner_admin" {
+  for_each = nonsensitive({ for pair in local.namespace_owner_pairs : "${pair.user_key}-${pair.namespace}" => pair })
+
+  metadata {
+    name      = "dashboard-owner-${each.value.user_key}"
+    namespace = each.value.namespace
+  }
+
+  role_ref {
+    api_group = "rbac.authorization.k8s.io"
+    kind      = "ClusterRole"
+    name      = "admin"
+  }
+
+  subject {
+    kind      = "ServiceAccount"
+    name      = kubernetes_service_account.dashboard_owner[each.key].metadata[0].name
+    namespace = each.value.namespace
+  }
+}
+
+# Cluster-wide read-only so the dashboard nav (namespaces, nodes, etc.) renders.
+resource "kubernetes_cluster_role_binding" "dashboard_owner_readonly" {
+  for_each = nonsensitive({ for pair in local.namespace_owner_pairs : "${pair.user_key}-${pair.namespace}" => pair })
+
+  metadata {
+    name = "dashboard-readonly-${each.value.user_key}-${each.value.namespace}"
+  }
+
+  role_ref {
+    api_group = "rbac.authorization.k8s.io"
+    kind      = "ClusterRole"
+    name      = kubernetes_cluster_role.namespace_owner_readonly.metadata[0].name
+  }
+
+  subject {
+    kind      = "ServiceAccount"
+    name      = kubernetes_service_account.dashboard_owner[each.key].metadata[0].name
+    namespace = each.value.namespace
+  }
+}
+
+# Long-lived (non-expiring) token the user pastes into the dashboard login.
+resource "kubernetes_secret" "dashboard_owner_token" {
+  for_each = nonsensitive({ for pair in local.namespace_owner_pairs : "${pair.user_key}-${pair.namespace}" => pair })
+
+  metadata {
+    name      = "dashboard-${each.value.user_key}-token"
+    namespace = each.value.namespace
+    annotations = {
+      "kubernetes.io/service-account.name" = kubernetes_service_account.dashboard_owner[each.key].metadata[0].name
+    }
+  }
+  type                           = "kubernetes.io/service-account-token"
+  wait_for_service_account_token = true
+}