- pact.HasAdminActionExtensions / AdminActionExtension: plugins add record
actions to any admin controller by ID, merged at boot before permission
validation (unknown target, no preview, duplicate name stop the boot)
- internal summercms.cabana pseudo-plugin, appended only when some plugin
registers admin controllers: Administrators list and preview, settings
link under System, backend.manage_users and backend.manage_roles with no
role grants
- backend::lang user, user.role and permissions copy (en, pl)
- smoke tests: compile-time seam and settings, Postgres list/preview/action
