[Viewer] Black screen after remote user logs out

[ToddHebebrand]

Description

After the remote user logs out of their session, the Breeze Viewer continues showing a black screen instead of handling the session end gracefully.

Current behavior: Viewer stays connected showing a black screen with 0 FPS after the remote user logs out.

Expected behavior: Viewer should detect the session ended and either:

• Show a "Session ended" message with option to reconnect
• Automatically attempt to reconnect to the login screen
• Gracefully close the connection with a clear status message

Affected Components

• Breeze Viewer (desktop app)
• Remote desktop WebRTC stream handling

Screenshots

Viewer showing 0 FPS black screen after remote logout — WebRTC connection still active but no frames being captured.

[ToddHebebrand]

Update: Related fixes have landed but this specific scenario (black screen after remote user logout) is not yet handled:

• acb23395 / 98fc7753 — Fixed black screen on headless servers (no GPU)
• Session switcher (6021164b) lets users manually reconnect to a different session

This issue is closely related to #330 (auto-reconnect on handoff). Once the desktop_handoff message is implemented, the viewer would automatically detect the logout and either reconnect to the login screen or show a "session ended" message.