feat: implement gate authentication with login and logout functionality

app/Http/Middleware/GateAuth.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class GateAuth
+{
+    public function handle(Request $request, Closure $next): Response
+    {
+        // Allow the login routes through without auth check
+        if ($request->routeIs('gate.login', 'gate.attempt', 'gate.logout')) {
+            return $next($request);
+        }
+
+        if (! $request->session()->get('gate_authenticated')) {
+            return redirect()->route('gate.login');
+        }
+
+        return $next($request);
+    }
+}