Enhance API functionality and security: Added rate limiting and domain validation across multiple API endpoints, improved error handling for missing or invalid parameters, and refactored email handling in contact form for better security and maintainability. Updated README.md with production build instructions and prerequisites.

backend/includes/footer.php

@@ -160,7 +160,7 @@
     <script src="/assets/js/cookie-consent.js" defer></script>
     <?php if (isset($additional_scripts)): ?>
         <?php foreach ($additional_scripts as $script): ?>
-            <script src="<?php echo $script; ?>" defer></script>
+            <script src="<?php echo htmlspecialchars($script, ENT_QUOTES, 'UTF-8'); ?>" defer></script>
         <?php endforeach; ?>
     <?php endif; ?>
 </body>