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/http-client/Response/HttplugPromise.php

@@ -0,0 +1,71 @@
+<?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\HttpClient\Response;
+
+use GuzzleHttp\Promise\Create;
+use GuzzleHttp\Promise\PromiseInterface as GuzzlePromiseInterface;
+use Http\Promise\Promise as HttplugPromiseInterface;
+use Psr\Http\Message\ResponseInterface as Psr7ResponseInterface;
+
+/**
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ *
+ * @internal
+ */
+final class HttplugPromise implements HttplugPromiseInterface
+{
+    public function __construct(
+        private GuzzlePromiseInterface $promise,
+    ) {
+    }
+
+    public function then(?callable $onFulfilled = null, ?callable $onRejected = null): self
+    {
+        return new self($this->promise->then(
+            $this->wrapThenCallback($onFulfilled),
+            $this->wrapThenCallback($onRejected)
+        ));
+    }
+
+    public function cancel(): void
+    {
+        $this->promise->cancel();
+    }
+
+    public function getState(): string
+    {
+        return $this->promise->getState();
+    }
+
+    /**
+     * @return Psr7ResponseInterface|mixed
+     */
+    public function wait($unwrap = true): mixed
+    {
+        $result = $this->promise->wait($unwrap);
+
+        while ($result instanceof HttplugPromiseInterface || $result instanceof GuzzlePromiseInterface) {
+            $result = $result->wait($unwrap);
+        }
+
+        return $result;
+    }
+
+    private function wrapThenCallback(?callable $callback): ?callable
+    {
+        if (null === $callback) {
+            return null;
+        }
+
+        return static fn ($value) => Create::promiseFor($callback($value));
+    }
+}