WinForms tests open real windows that take focus from the user's work.
Test-Hidden.ps1 runs them on a separate Win32 desktop in the same window
station, so forms keep real handles and message loops while nothing appears.
A job object ends the whole tree on any exit, and a timeout stops runs stuck
on a modal dialog nobody can dismiss there.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
