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/Internal/AmpBody.php

@@ -0,0 +1,150 @@
+<?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\Internal;
+
+use Amp\ByteStream\ReadableBuffer;
+use Amp\ByteStream\ReadableIterableStream;
+use Amp\ByteStream\ReadableResourceStream;
+use Amp\ByteStream\ReadableStream;
+use Amp\Cancellation;
+use Amp\Http\Client\HttpContent;
+use Symfony\Component\HttpClient\Exception\TransportException;
+
+/**
+ * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @internal
+ */
+class AmpBody implements HttpContent, ReadableStream, \IteratorAggregate
+{
+    private ReadableStream $body;
+    private ?string $content;
+    private array $info;
+    private ?int $offset = 0;
+    private int $length = -1;
+    private ?int $uploaded = null;
+
+    /**
+     * @param \Closure|resource|string $body
+     */
+    public function __construct(
+        $body,
+        &$info,
+        private \Closure $onProgress,
+    ) {
+        $this->info = &$info;
+
+        if (\is_resource($body)) {
+            $this->offset = ftell($body);
+            $this->length = fstat($body)['size'];
+            $this->body = new ReadableResourceStream($body);
+        } elseif (\is_string($body)) {
+            $this->length = \strlen($body);
+            $this->body = new ReadableBuffer($body);
+            $this->content = $body;
+        } else {
+            $this->body = new ReadableIterableStream((static function () use ($body) {
+                while ('' !== $data = ($body)(16372)) {
+                    if (!\is_string($data)) {
+                        throw new TransportException(\sprintf('Return value of the "body" option callback must be string, "%s" returned.', get_debug_type($data)));
+                    }
+
+                    yield $data;
+                }
+            })());
+        }
+    }
+
+    public function getContent(): ReadableStream
+    {
+        if (null !== $this->uploaded) {
+            $this->uploaded = null;
+
+            if (\is_string($this->body)) {
+                $this->offset = 0;
+            } elseif ($this->body instanceof ReadableResourceStream) {
+                fseek($this->body->getResource(), $this->offset);
+            }
+        }
+
+        return $this;
+    }
+
+    public function getContentType(): ?string
+    {
+        return null;
+    }
+
+    public function getContentLength(): ?int
+    {
+        return 0 <= $this->length ? $this->length - $this->offset : null;
+    }
+
+    public function read(?Cancellation $cancellation = null): ?string
+    {
+        $this->info['size_upload'] += $this->uploaded;
+        $this->uploaded = 0;
+        ($this->onProgress)();
+
+        if (null !== $data = $this->body->read($cancellation)) {
+            $this->uploaded = \strlen($data);
+        } else {
+            $this->info['upload_content_length'] = $this->info['size_upload'];
+        }
+
+        return $data;
+    }
+
+    public function isReadable(): bool
+    {
+        return $this->body->isReadable();
+    }
+
+    public function close(): void
+    {
+        $this->body->close();
+    }
+
+    public function isClosed(): bool
+    {
+        return $this->body->isClosed();
+    }
+
+    public function onClose(\Closure $onClose): void
+    {
+        $this->body->onClose($onClose);
+    }
+
+    public function getIterator(): \Traversable
+    {
+        return $this->body;
+    }
+
+    public static function rewind(HttpContent $body): HttpContent
+    {
+        if (!$body instanceof self) {
+            return $body;
+        }
+
+        $body->uploaded = null;
+
+        if ($body->body instanceof ReadableResourceStream && !$body->body->isClosed()) {
+            fseek($body->body->getResource(), $body->offset);
+        }
+
+        if ($body->body instanceof ReadableBuffer) {
+            return new $body($body->content, $body->info, $body->onProgress);
+        }
+
+        return $body;
+    }
+}