feat: add HarRecorder PSR-18 client decorator for recording HTTP traffic (#245)

Implement a PSR-18 HTTP client decorator that records request/response
pairs to HAR format. This enables generating test fixtures by recording
real API interactions.

Example usage:
```
    $recorder = new HarRecorder($actualHttpClient);
    $response = $recorder->sendRequest($request);
    $har = $recorder->getHar();
```

Features:
- Records timing information for each request
- Supports custom creator name/version
- Provides entry count and reset functionality
- Fully serializable HAR output

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: deviantintegral

composer.json

@@ -17,6 +17,7 @@
         "jms/serializer": "^3.0",
         "doctrine/annotations": "^2.0",
         "guzzlehttp/psr7": "^2.0",
+        "psr/http-client": "^1.0",
         "deviantintegral/jms-serializer-uri-handler": "^1.1",
         "deviantintegral/null-date-time": "^1.0",
         "symfony/console": "^7||^8"

src/HarRecorder.php

@@ -0,0 +1,113 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Deviantintegral\Har;
+
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * A PSR-18 HTTP client decorator that records request/response traffic to HAR format.
+ *
+ * Use case: Generate test fixtures by recording real API interactions.
+ *
+ * Example usage:
+ *     $recorder = new HarRecorder($actualHttpClient);
+ *     $response = $recorder->sendRequest($request);  // Makes real request
+ *     $har = $recorder->getHar();  // Get recorded traffic
+ */
+final class HarRecorder implements ClientInterface
+{
+    /**
+     * @var Entry[]
+     */
+    private array $entries = [];
+
+    private Creator $creator;
+
+    /**
+     * @param ClientInterface $client         The underlying HTTP client to delegate requests to
+     * @param string          $creatorName    Name of the application creating the HAR
+     * @param string          $creatorVersion Version of the application
+     */
+    public function __construct(
+        private readonly ClientInterface $client,
+        string $creatorName = 'deviantintegral/har',
+        string $creatorVersion = '1.0',
+    ) {
+        $this->creator = (new Creator())
+            ->setName($creatorName)
+            ->setVersion($creatorVersion);
+    }
+
+    /**
+     * Send an HTTP request and record the request/response pair.
+     *
+     * @throws \Psr\Http\Client\ClientExceptionInterface
+     */
+    public function sendRequest(RequestInterface $request): ResponseInterface
+    {
+        $startTime = hrtime(true);
+        $startDateTime = new \DateTime();
+
+        $response = $this->client->sendRequest($request);
+
+        $endTime = hrtime(true);
+        /** @infection-ignore-all Equivalent mutant: 1 part per million difference is not testable */
+        $totalTimeMs = ($endTime - $startTime) / 1_000_000;
+
+        $entry = $this->createEntry($request, $response, $startDateTime, $totalTimeMs);
+        $this->entries[] = $entry;
+
+        return $response;
+    }
+
+    /**
+     * Get the recorded traffic as a HAR object.
+     */
+    public function getHar(): Har
+    {
+        $log = (new Log())
+            ->setVersion('1.2')
+            ->setCreator($this->creator)
+            ->setEntries($this->entries);
+
+        return (new Har())->setLog($log);
+    }
+
+    /**
+     * Reset and clear all recorded entries.
+     */
+    public function reset(): void
+    {
+        $this->entries = [];
+    }
+
+    /**
+     * Create a HAR entry from the request/response pair.
+     */
+    private function createEntry(
+        RequestInterface $request,
+        ResponseInterface $response,
+        \DateTime $startDateTime,
+        float $totalTimeMs,
+    ): Entry {
+        $harRequest = Request::fromPsr7Request($request);
+        $harResponse = Response::fromPsr7Response($response);
+
+        $timings = (new Timings())
+            ->setSend(0)
+            ->setWait($totalTimeMs)
+            ->setReceive(0);
+
+        return (new Entry())
+            ->setStartedDateTime($startDateTime)
+            ->setTime($totalTimeMs)
+            ->setRequest($harRequest)
+            ->setResponse($harResponse)
+            ->setCache(new Cache())
+            ->setTimings($timings);
+    }
+}