Add Rails admin

app/policies/application_policy.rb

@@ -76,4 +76,7 @@ class ApplicationPolicy
     end
     private :require_user!
   end
+  [:dashboard?, :index?, :new?, :export?, :bulk_delete?, :show?, :edit?, :delete?, :show_in_app?,].each do |action|
+    define_method(action) { admin? }
+  end
 end

app/views/application/_navigation.html.slim

@@ -7,6 +7,7 @@
       ul.dropdown-menu.p-0.mt-1 role='menu'
         - if current_user.admin?
           li = link_to(t('breadcrumbs.dashboard.show'), admin_dashboard_path, class: 'dropdown-item', 'data-turbolinks' => "false") if policy([:admin, :dashboard]).show?
+          li = link_to(t('breadcrumbs.rails_admin.show'), rails_admin.dashboard_path, class: 'dropdown-item', 'data-turbolinks' => "false") if policy([:admin, :dashboard]).show?
           li = link_to(t('breadcrumbs.statistics.show'), statistics_path, class: 'dropdown-item') if policy(:statistics).show?
           li.dropdown-divider role='separator'
         = render('navigation_submenu', title: t('activerecord.models.exercise.other'),