feat: add MCP server for the website chatbot over a mirrored TYPO3 content feed

src/ContentFeed/Exception/ContentFeedUnavailableException.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\ContentFeed\Exception;
+
+/**
+ * TYPO3 answered 503: the feed has been switched off on its side.
+ */
+class ContentFeedUnavailableException extends ContentFeedStoppedException
+{
+    public function __construct(public readonly ?\DateTimeImmutable $retryAfter)
+    {
+        parent::__construct('TYPO3 switched the content feed off (503)'.(null !== $retryAfter ? ', retry after '.$retryAfter->format('c') : ''));
+    }
+}