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/config/Loader/DelegatingLoader.php

@@ -0,0 +1,44 @@
+<?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\Config\Loader;
+
+use Symfony\Component\Config\Exception\LoaderLoadException;
+
+/**
+ * DelegatingLoader delegates loading to other loaders using a loader resolver.
+ *
+ * This loader acts as an array of LoaderInterface objects - each having
+ * a chance to load a given resource (handled by the resolver)
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class DelegatingLoader extends Loader
+{
+    public function __construct(LoaderResolverInterface $resolver)
+    {
+        $this->resolver = $resolver;
+    }
+
+    public function load(mixed $resource, ?string $type = null): mixed
+    {
+        if (false === $loader = $this->resolver->resolve($resource, $type)) {
+            throw new LoaderLoadException($resource, null, 0, null, $type);
+        }
+
+        return $loader->load($resource, $type);
+    }
+
+    public function supports(mixed $resource, ?string $type = null): bool
+    {
+        return false !== $this->resolver->resolve($resource, $type);
+    }
+}