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/Definition/Exception/InvalidConfigurationException.php

@@ -0,0 +1,52 @@
+<?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\Definition\Exception;
+
+/**
+ * A very general exception which can be thrown whenever non of the more specific
+ * exceptions is suitable.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+class InvalidConfigurationException extends Exception
+{
+    private ?string $path = null;
+    private bool $containsHints = false;
+
+    /**
+     * @return void
+     */
+    public function setPath(string $path)
+    {
+        $this->path = $path;
+    }
+
+    public function getPath(): ?string
+    {
+        return $this->path;
+    }
+
+    /**
+     * Adds extra information that is suffixed to the original exception message.
+     *
+     * @return void
+     */
+    public function addHint(string $hint)
+    {
+        if (!$this->containsHints) {
+            $this->message .= "\nHint: ".$hint;
+            $this->containsHints = true;
+        } else {
+            $this->message .= ', '.$hint;
+        }
+    }
+}