This page drives the browser DevTools WebSocket directly from HTML. It opens
a short-lived target, issues IndexedDB.requestData, and then
navigates the target away to trigger the browser-side teardown race.
Start the browser with --remote-debugging-port=9239 --remote-allow-origins=*.
If auto-discovery fails, open http://127.0.0.1:9239/json/version,
copy webSocketDebuggerUrl, and paste it below.