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/Exception/ServiceCircularReferenceException.php

@@ -0,0 +1,47 @@
+<?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\Exception;
+
+/**
+ * This exception is thrown when a circular reference is detected.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+class ServiceCircularReferenceException extends RuntimeException
+{
+    private string $serviceId;
+    private array $path;
+
+    public function __construct(string $serviceId, array $path, ?\Throwable $previous = null)
+    {
+        parent::__construct(\sprintf('Circular reference detected for service "%s", path: "%s".', $serviceId, implode(' -> ', $path)), 0, $previous);
+
+        $this->serviceId = $serviceId;
+        $this->path = $path;
+    }
+
+    /**
+     * @return string
+     */
+    public function getServiceId()
+    {
+        return $this->serviceId;
+    }
+
+    /**
+     * @return array
+     */
+    public function getPath()
+    {
+        return $this->path;
+    }
+}