Add safe_html() for XSS-safe WYSIWYG HTML sanitization

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

vendor/ezyang/htmlpurifier/library/HTMLPurifier/HTMLModule/Nofollow.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * Module adds the nofollow attribute transformation to a tags.  It
+ * is enabled by HTML.Nofollow
+ */
+class HTMLPurifier_HTMLModule_Nofollow extends HTMLPurifier_HTMLModule
+{
+
+    /**
+     * @type string
+     */
+    public $name = 'Nofollow';
+
+    /**
+     * @param HTMLPurifier_Config $config
+     */
+    public function setup($config)
+    {
+        $a = $this->addBlankElement('a');
+        $a->attr_transform_post[] = new HTMLPurifier_AttrTransform_Nofollow();
+    }
+}
+
+// vim: et sw=4 sts=4