feat: add webshop offline maintenance mode with admin toggle and red maintenance screen

bootstrap/app.php

@@ -1,5 +1,6 @@
 <?php
 
+use App\Http\Middleware\CheckWebshopOffline;
 use App\Http\Middleware\EnsureUserIsAdmin;
 use Illuminate\Foundation\Application;
 use Illuminate\Foundation\Configuration\Exceptions;
@@ -14,6 +15,9 @@ return Application::configure(basePath: dirname(__DIR__))
     )
     ->withMiddleware(function (Middleware $middleware): void {
         $middleware->trustProxies(at: '*');
+        $middleware->web(append: [
+            CheckWebshopOffline::class,
+        ]);
         $middleware->alias([
             'admin' => EnsureUserIsAdmin::class,
         ]);