Initial commit: Grav CMS setup with HTML reference material

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/email/vendor/symfony/messenger/Exception/UnrecoverableMessageHandlingException.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Messenger\Exception;
+
+/**
+ * A concrete implementation of UnrecoverableExceptionInterface that can be used directly.
+ *
+ * @author Frederic Bouchery <frederic@bouchery.fr>
+ */
+class UnrecoverableMessageHandlingException extends RuntimeException implements UnrecoverableExceptionInterface
+{
+}