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/Extension/AbstractExtension.php

@@ -0,0 +1,65 @@
+<?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\Extension;
+
+use Symfony\Component\Config\Definition\Configuration;
+use Symfony\Component\Config\Definition\ConfigurationInterface;
+use Symfony\Component\Config\Definition\Configurator\DefinitionConfigurator;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+
+/**
+ * An Extension that provides configuration hooks.
+ *
+ * @author Yonel Ceruto <yonelceruto@gmail.com>
+ */
+abstract class AbstractExtension extends Extension implements ConfigurableExtensionInterface, PrependExtensionInterface
+{
+    use ExtensionTrait;
+
+    public function configure(DefinitionConfigurator $definition): void
+    {
+    }
+
+    public function prependExtension(ContainerConfigurator $container, ContainerBuilder $builder): void
+    {
+    }
+
+    public function loadExtension(array $config, ContainerConfigurator $container, ContainerBuilder $builder): void
+    {
+    }
+
+    public function getConfiguration(array $config, ContainerBuilder $container): ?ConfigurationInterface
+    {
+        return new Configuration($this, $container, $this->getAlias());
+    }
+
+    final public function prepend(ContainerBuilder $container): void
+    {
+        $callback = function (ContainerConfigurator $configurator) use ($container) {
+            $this->prependExtension($configurator, $container);
+        };
+
+        $this->executeConfiguratorCallback($container, $callback, $this);
+    }
+
+    final public function load(array $configs, ContainerBuilder $container): void
+    {
+        $config = $this->processConfiguration($this->getConfiguration([], $container), $configs);
+
+        $callback = function (ContainerConfigurator $configurator) use ($config, $container) {
+            $this->loadExtension($config, $configurator, $container);
+        };
+
+        $this->executeConfiguratorCallback($container, $callback, $this);
+    }
+}