fix sse error handling if shop api error part 2

src/Shopware/StoreApiClient.php

@@ -49,7 +49,11 @@ final readonly class StoreApiClient
                 'sw-access-key' => $this->salesChannelAccessKey,
             ],
             'body' => $body,
+            // Keep Shopware calls bounded. During SSE responses the browser only
+            // receives data between blocking HTTP calls, so long Store API waits
+            // can look like a broken stream to proxies or the browser.
             'timeout' => $this->timeoutSeconds,
+            'max_duration' => max(1, $this->timeoutSeconds + 1),
         ]);
 
         $statusCode = $response->getStatusCode();