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/html-sanitizer/Visitor/AttributeSanitizer/UrlAttributeSanitizer.php

@@ -0,0 +1,53 @@
+<?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\HtmlSanitizer\Visitor\AttributeSanitizer;
+
+use Symfony\Component\HtmlSanitizer\HtmlSanitizerConfig;
+use Symfony\Component\HtmlSanitizer\TextSanitizer\UrlSanitizer;
+
+/**
+ * @author Titouan Galopin <galopintitouan@gmail.com>
+ */
+final class UrlAttributeSanitizer implements AttributeSanitizerInterface
+{
+    public function getSupportedElements(): ?array
+    {
+        // Check all elements for URL attributes
+        return null;
+    }
+
+    public function getSupportedAttributes(): ?array
+    {
+        return ['src', 'href', 'lowsrc', 'background', 'ping', 'action', 'formaction', 'poster', 'cite', 'data', 'codebase', 'archive', 'longdesc'];
+    }
+
+    public function sanitizeAttribute(string $element, string $attribute, string $value, HtmlSanitizerConfig $config): ?string
+    {
+        if (\in_array($element, ['a', 'area'], true) || \in_array($attribute, ['action', 'formaction', 'cite'], true)) {
+            return UrlSanitizer::sanitize(
+                $value,
+                $config->getAllowedLinkSchemes(),
+                $config->getForceHttpsUrls(),
+                $config->getAllowedLinkHosts(),
+                $config->getAllowRelativeLinks(),
+            );
+        }
+
+        return UrlSanitizer::sanitize(
+            $value,
+            $config->getAllowedMediaSchemes(),
+            $config->getForceHttpsUrls(),
+            $config->getAllowedMediaHosts(),
+            $config->getAllowRelativeMedias(),
+        );
+    }
+}