feat(ntfy): add admin Notifications settings page with test button

config/routes.rb

@@ -66,6 +66,10 @@ Rails.application.routes.draw do
     end
 
     get "api_tester", to: "api_tester#index"
+
+    resource :notifications, only: [:show, :update] do
+      post :test
+    end
   end
 
   # Root route