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/contracts/Service/Attribute/Required.php

@@ -0,0 +1,25 @@
+<?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\Contracts\Service\Attribute;
+
+/**
+ * A required dependency.
+ *
+ * This attribute indicates that a property holds a required dependency. The annotated property or method should be
+ * considered during the instantiation process of the containing class.
+ *
+ * @author Alexander M. Turek <me@derrabus.de>
+ */
+#[\Attribute(\Attribute::TARGET_METHOD | \Attribute::TARGET_PROPERTY)]
+final class Required
+{
+}