Copilot window can become stuck always on top until app restart

### Description

The GitHub Copilot App somehow entered a persistent topmost window state on Windows. After that happened, the main Copilot window remained in front of every other application when I switched focus, covering those apps.

There was no visible always-on-top or pin control in the title bar or app UI, and I do not have PowerToys installed, so this was not caused by PowerToys' Always On Top feature.

### Reproduction

I do not yet know what action triggered the state. The app had been used normally across multiple sessions and eventually began behaving as an always-on-top window.

### Actual behavior

The Copilot window stayed above all other application windows even after another app received focus.

### Expected behavior

Unless explicitly requested by the user, the Copilot window should follow normal Windows z-order and move behind the active application.

### Workaround

Fully restarting the GitHub Copilot App cleared the topmost state and restored normal window behavior.

### Environment

- GitHub Copilot App: 1.1.10
- Windows: 10.0.26200.0
- PowerToys: not installed

Comienza reproduciendo el comportamiento persistente de always-on-top en Windows utilizando las versiones indicadas de la app y del OS; después, inspecciona la gestión del estado de las ventanas del escritorio. Confirma qué acción o ciclo de vida deja la ventana como topmost y verifica que los cambios normales de foco restauren el z-order estándar sin requerir reiniciar la app.

Escrito por el modelo de indexación a partir del texto del issue.