refactor: Cleanup git state - commit all staged changes

Major refactoring cleanup:
- Add new controller architecture (class-controller-*.php)
- Add new settings-v2 UI (views/settings-v2/)
- Add new CSS architecture (agentic-sidebar.css, tokens)
- Add esbuild build pipeline (scripts/build.js, package.json)
- Add composer dependencies (vendor/)
- Add frontend src directory (assets/js/src/index.jsx)
- Add documentation files
- Remove old/obsolete files (class-settings.php, old CSS)

This commits all pending changes from previous refactoring efforts.

vendor/symfony/html-sanitizer/Visitor/Node/TextNode.php

@@ -0,0 +1,41 @@
+<?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\HtmlSanitizer\Visitor\Node;
+
+use Symfony\Component\HtmlSanitizer\TextSanitizer\StringSanitizer;
+
+/**
+ * @author Titouan Galopin <galopintitouan@gmail.com>
+ */
+final class TextNode implements NodeInterface
+{
+    public function __construct(
+        private NodeInterface $parentNode,
+        private string $text,
+    ) {
+    }
+
+    public function addChild(NodeInterface $node): void
+    {
+        throw new \LogicException('Text nodes cannot have children.');
+    }
+
+    public function getParent(): ?NodeInterface
+    {
+        return $this->parentNode;
+    }
+
+    public function render(): string
+    {
+        return StringSanitizer::encodeHtmlEntities($this->text);
+    }
+}