feat(demo): add story 1 — Sorano: Rock and Time

plugins/api/classes/Api/Exceptions/TooManyRequestsException.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Grav\Plugin\Api\Exceptions;
+
+class TooManyRequestsException extends ApiException
+{
+    public function __construct(string $detail = 'Too many requests.', int $retryAfter = 0, ?\Throwable $previous = null)
+    {
+        $headers = [];
+        if ($retryAfter > 0) {
+            $headers['Retry-After'] = (string) $retryAfter;
+        }
+        parent::__construct(429, 'Too Many Requests', $detail, $headers, $previous);
+    }
+}