Black Screen

### Description of the new feature / enhancement

Keyboard shortcut to black-out and restore all screens (instead of Win-L which requires the windows login password)

### Scenario when this would be used?

-

### Supporting information

_No response_

The issue does not name files, tests, or an entry point. Begin by locating the existing keyboard-shortcut handling and screen-display control in PowerToys, then clarify the intended blackout and restore behavior for all screens. Done should include a shortcut that blacks out and restores every screen without requiring the Windows login password.

Written by the indexing model from the issue text.