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/routing/Exception/MissingMandatoryParametersException.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\Routing\Exception;
+
+/**
+ * Exception thrown when a route cannot be generated because of missing
+ * mandatory parameters.
+ *
+ * @author Alexandre Salomé <alexandre.salome@gmail.com>
+ */
+class MissingMandatoryParametersException extends \InvalidArgumentException implements ExceptionInterface
+{
+    private string $routeName = '';
+    private array $missingParameters = [];
+
+    /**
+     * @param string[] $missingParameters
+     * @param int      $code
+     */
+    public function __construct(string $routeName = '', $missingParameters = null, $code = 0, ?\Throwable $previous = null)
+    {
+        if (\is_array($missingParameters)) {
+            $this->routeName = $routeName;
+            $this->missingParameters = $missingParameters;
+            $message = \sprintf('Some mandatory parameters are missing ("%s") to generate a URL for route "%s".', implode('", "', $missingParameters), $routeName);
+        } else {
+            trigger_deprecation('symfony/routing', '6.1', 'Construction of "%s" with an exception message is deprecated, provide the route name and an array of missing parameters instead.', __CLASS__);
+            $message = $routeName;
+            $previous = $code instanceof \Throwable ? $code : null;
+            $code = (int) $missingParameters;
+        }
+
+        parent::__construct($message, $code, $previous);
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getMissingParameters(): array
+    {
+        return $this->missingParameters;
+    }
+
+    public function getRouteName(): string
+    {
+        return $this->routeName;
+    }
+}