Add copyright headers to all application files

Added copyright headers to all PHP files in the application with proper author information (Martin Kiesewetter) and contact details.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/classes/Crawler.php

@@ -1,5 +1,13 @@
 <?php
 
+/**
+ * Web Crawler - Crawler Class
+ *
+ * @copyright Copyright (c) 2025 Martin Kiesewetter
+ * @author    Martin Kiesewetter <mki@kies-media.de>
+ * @link      https://kies-media.de
+ */
+
 namespace App;
 
 use GuzzleHttp\Client;