feat: implement gate authentication with login and logout functionality

app/Http/Controllers/GateController.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers;
+
+use Illuminate\Http\RedirectResponse;
+use Illuminate\Http\Request;
+use Illuminate\View\View;
+
+class GateController extends Controller
+{
+    public function login(): View
+    {
+        return view('gate.login');
+    }
+
+    public function attempt(Request $request): RedirectResponse
+    {
+        $request->validate([
+            'password' => 'required|string',
+        ]);
+
+        $expected = config('app.password');
+
+        if (! $expected || $request->input('password') !== $expected) {
+            return back()->withErrors(['password' => 'Wrong password. Please try again.']);
+        }
+
+        // Store flag in session; expires with session lifetime (24 h in .env)
+        $request->session()->put('gate_authenticated', true);
+        $request->session()->regenerate();
+
+        return redirect()->intended(route('dashboard'));
+    }
+
+    public function logout(Request $request): RedirectResponse
+    {
+        $request->session()->forget('gate_authenticated');
+        $request->session()->regenerate();
+
+        return redirect()->route('gate.login');
+    }
+}

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);
+    }
+}