feat: add guestbook with rate limiting (#6)

* Re-add guestbook w/ rate limiting
* Add guestbook to navbar

app/Http/Middleware/RateLimiter.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Cache;
+use Symfony\Component\HttpFoundation\Response;
+
+class RateLimiter
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        $ipAddress = $request->ip();
+        $cacheKey = 'rate_limit_' . $ipAddress;
+
+        if (Cache::has($cacheKey)) {
+            // If the cache key exists, the IP has submitted an entry within the last hour
+            return response()->view('errors.ratelimit-guestbook', [], 429);
+        }
+
+        // Add the IP address to the cache and set the expiration time to one hour
+        Cache::put($cacheKey, true, 60);
+
+        return $next($request);
+    }
+}