Wire Rancher to Authentik ak_groups + akP-rancher global roles

Consume the two-tier Authentik RBAC (terraform-authentik): read the hierarchical
`ak_groups` claim and grant Rancher global roles to the akP-rancher permission
groups. Members of akR-global-admin/akR-standard-user inherit these.

- keycloakoidc: scopes += ak_groups; groups_field = ak_groups
- global_role_bindings: akP-rancher-admin -> admin, akP-rancher-user -> user
  (group principal keycloakoidc_group://<name>)

config/config.hcl

@@ -8,5 +8,10 @@ locals {
 
   config = {
     keycloakoidc = try(local.all_configs["keycloakoidc.yaml"], null)
+    global_role_bindings = {
+      for file_path, content in local.all_configs :
+      trimsuffix(basename(file_path), ".yaml") => content
+      if startswith(file_path, "global_role_bindings/")
+    }
   }
 }