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/league/uri-interfaces/FeatureDetection.php

@@ -0,0 +1,64 @@
+<?php
+
+/**
+ * League.Uri (https://uri.thephpleague.com)
+ *
+ * (c) Ignace Nyamagana Butera <nyamsprod@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace League\Uri;
+
+use finfo;
+use League\Uri\Exceptions\MissingFeature;
+use League\Uri\IPv4\Calculator;
+
+use function class_exists;
+use function defined;
+use function extension_loaded;
+use function function_exists;
+
+use const PHP_INT_SIZE;
+
+/**
+ * Allow detecting features needed to make the packages work.
+ */
+final class FeatureDetection
+{
+    public static function supportsFileDetection(): void
+    {
+        static $isSupported = null;
+        $isSupported = $isSupported ?? class_exists(finfo::class);
+
+        $isSupported || throw new MissingFeature('Support for file type detection requires the `fileinfo` extension.');
+
+    }
+
+    public static function supportsIdn(): void
+    {
+        static $isSupported = null;
+        $isSupported = $isSupported ?? (function_exists('\idn_to_ascii') && defined('\INTL_IDNA_VARIANT_UTS46'));
+
+        $isSupported || throw new MissingFeature('Support for IDN host requires the `intl` extension for best performance or run "composer require symfony/polyfill-intl-idn" to install a polyfill.');
+    }
+
+    public static function supportsIPv4Conversion(): void
+    {
+        static $isSupported = null;
+        $isSupported = $isSupported ?? (extension_loaded('gmp') || extension_loaded('bcmath') || (4 < PHP_INT_SIZE));
+
+        $isSupported || throw new MissingFeature('A '.Calculator::class.' implementation could not be automatically loaded. To perform IPv4 conversion use a x.64 PHP build or install one of the following extension GMP or BCMath. You can also ship your own implementation.');
+    }
+
+    public static function supportsDom(): void
+    {
+        static $isSupported = null;
+        $isSupported = $isSupported ?? extension_loaded('dom');
+
+        $isSupported || throw new MissingFeature('To use a DOM related feature, the DOM extension must be installed in your system.');
+    }
+}