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/polyfill-php80/Resources/stubs/Attribute.php

@@ -0,0 +1,31 @@
+<?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.
+ */
+
+#[Attribute(Attribute::TARGET_CLASS)]
+final class Attribute
+{
+    public const TARGET_CLASS = 1;
+    public const TARGET_FUNCTION = 2;
+    public const TARGET_METHOD = 4;
+    public const TARGET_PROPERTY = 8;
+    public const TARGET_CLASS_CONSTANT = 16;
+    public const TARGET_PARAMETER = 32;
+    public const TARGET_ALL = 63;
+    public const IS_REPEATABLE = 64;
+
+    /** @var int */
+    public $flags;
+
+    public function __construct(int $flags = self::TARGET_ALL)
+    {
+        $this->flags = $flags;
+    }
+}