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

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;
+    }
+}