`clear()` throws error (`The element to be cleared could not be focused`) in shadow DOM

Reproduction example

https://stackblitz.com/edit/js-4pfvam?file=index.js

Prerequisites

To repro, create an <input> in a shadow root, and then try to clear() it:

import userEvent from '@testing-library/user-event';

const appDiv = document.getElementById('app');

appDiv.attachShadow({ mode: 'open' }).innerHTML = '<input type=text>';
const input = appDiv.shadowRoot.querySelector('input');

userEvent.clear(input); // throws the Error

Expected behavior

An <input> should be clear()able regardless of whether it's in a shadow root or not. It's still focusable, even if it's in a shadow root.

Actual behavior

The error is thrown: The element to be cleared could not be focused

The root cause seems to be this line of code:

https://github.com/testing-library/user-event/blob/7a305dee9ab833d6f338d567fc2e862b4838b76a/src/utility/clear.ts#L12C1-L14

The issue is that document.activeElement is not sufficient for determining the active element in this case. You would need to drill down one level deeper into the shadow root:

document.activeElement // shadow host element
document.activeElement.shadowRoot.activeElement // <input>

User-event version

14.4.3

Environment

See repro above.

Additional context

This used to work in a previous version of @testing-libray/user-event. It seems to have started throwing in this commit: https://github.com/testing-library/user-event/commit/1cda1b1b9726c2e7db213ec543f96b3fde2d10b8

Start with src/utility/clear.ts, especially the focus check identified in the issue, and reproduce the failure using the linked StackBlitz example. Trace how activeElement is resolved through the shadow root, then verify that clear() succeeds for the shadow-root input without regressing ordinary inputs.