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/dependency-injection/ExpressionLanguage.php

@@ -0,0 +1,37 @@
+<?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\DependencyInjection;
+
+use Psr\Cache\CacheItemPoolInterface;
+use Symfony\Component\ExpressionLanguage\ExpressionLanguage as BaseExpressionLanguage;
+
+if (!class_exists(BaseExpressionLanguage::class)) {
+    return;
+}
+
+/**
+ * Adds some function to the default ExpressionLanguage.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @see ExpressionLanguageProvider
+ */
+class ExpressionLanguage extends BaseExpressionLanguage
+{
+    public function __construct(?CacheItemPoolInterface $cache = null, array $providers = [], ?callable $serviceCompiler = null, ?\Closure $getEnv = null)
+    {
+        // prepend the default provider to let users override it easily
+        array_unshift($providers, new ExpressionLanguageProvider($serviceCompiler, $getEnv));
+
+        parent::__construct($cache, $providers);
+    }
+}