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/FileLocatorInterface.php

@@ -0,0 +1,36 @@
+<?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;
+
+use Symfony\Component\Config\Exception\FileLocatorFileNotFoundException;
+
+/**
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+interface FileLocatorInterface
+{
+    /**
+     * Returns a full path for a given file name.
+     *
+     * @param string      $name        The file name to locate
+     * @param string|null $currentPath The current path
+     * @param bool        $first       Whether to return the first occurrence or an array of filenames
+     *
+     * @return string|string[] The full path to the file or an array of file paths
+     *
+     * @psalm-return ($first is true ? string : string[])
+     *
+     * @throws \InvalidArgumentException        If $name is empty
+     * @throws FileLocatorFileNotFoundException If a file is not found
+     */
+    public function locate(string $name, ?string $currentPath = null, bool $first = true);
+}