security: add HTTP security headers, rate limiting on sensitive routes, and file upload extension validation

app/Http/Controllers/CartController.php

@@ -94,7 +94,7 @@ class CartController extends Controller
         $validated = $request->validate([
             'model_name' => 'nullable|string|max:255',
             'model_url' => 'nullable|url|max:1000',
-            'model_file' => 'nullable|file|max:51200', // 50MB
+            'model_file' => 'nullable|file|extensions:stl,3mf,obj,step,stp,zip|max:51200', // 50MB
             'size' => 'required|in:klein,medium,groot',
             'material' => 'required|string',
             'color' => 'required|string',

app/Http/Controllers/ShopController.php

@@ -106,7 +106,7 @@ class ShopController extends Controller
             'preferred_material' => 'nullable|string|max:50',
             'preferred_color' => 'nullable|string|max:50',
             'dimensions' => 'nullable|string|max:100',
-            'model_file' => 'nullable|file|max:51200', // max 50MB (stl, step, obj, zip)
+            'model_file' => 'nullable|file|extensions:stl,3mf,obj,step,stp,zip|max:51200', // max 50MB (stl, step, obj, zip)
         ]);
 
         $filePath = null;

app/Http/Middleware/AddSecurityHeaders.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class AddSecurityHeaders
+{
+    /**
+     * Handle an incoming request and append modern security headers.
+     *
+     * @param  Closure(Request): (Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        $response = $next($request);
+
+        $response->headers->set('X-Frame-Options', 'SAMEORIGIN');
+        $response->headers->set('X-Content-Type-Options', 'nosniff');
+        $response->headers->set('Referrer-Policy', 'strict-origin-when-cross-origin');
+        $response->headers->set('Permissions-Policy', 'camera=(), microphone=(), geolocation=()');
+
+        return $response;
+    }
+}