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/ExpressionLanguageProvider.php

@@ -0,0 +1,57 @@
+<?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 Symfony\Component\DependencyInjection\Exception\LogicException;
+use Symfony\Component\ExpressionLanguage\ExpressionFunction;
+use Symfony\Component\ExpressionLanguage\ExpressionFunctionProviderInterface;
+
+/**
+ * Define some ExpressionLanguage functions.
+ *
+ * To get a service, use service('request').
+ * To get a parameter, use parameter('kernel.debug').
+ * To get an env variable, use env('SOME_VARIABLE').
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class ExpressionLanguageProvider implements ExpressionFunctionProviderInterface
+{
+    private ?\Closure $serviceCompiler;
+
+    private ?\Closure $getEnv;
+
+    public function __construct(?callable $serviceCompiler = null, ?\Closure $getEnv = null)
+    {
+        $this->serviceCompiler = null === $serviceCompiler ? null : $serviceCompiler(...);
+        $this->getEnv = $getEnv;
+    }
+
+    public function getFunctions(): array
+    {
+        return [
+            new ExpressionFunction('service', $this->serviceCompiler ?? static fn ($arg) => \sprintf('$container->get(%s)', $arg), static fn (array $variables, $value) => $variables['container']->get($value)),
+
+            new ExpressionFunction('parameter', static fn ($arg) => \sprintf('$container->getParameter(%s)', $arg), static fn (array $variables, $value) => $variables['container']->getParameter($value)),
+
+            new ExpressionFunction('env', static fn ($arg) => \sprintf('$container->getEnv(%s)', $arg), function (array $variables, $value) {
+                if (!$this->getEnv) {
+                    throw new LogicException('You need to pass a getEnv closure to the expression language provider to use the "env" function.');
+                }
+
+                return ($this->getEnv)($value);
+            }),
+
+            new ExpressionFunction('arg', static fn ($arg) => \sprintf('$args?->get(%s)', $arg), static fn (array $variables, $value) => $variables['args']?->get($value)),
+        ];
+    }
+}