Fat Client macOS: Frequent notification when switching rooms while a room is active in the background

When using the Fat Client on macOS and switching between rooms while a room is actively working in the background, a notification popup is triggered every single time.

As a power user who handles multiple tasks in parallel and frequently switches contexts, this repetitive warning is disruptive and creates unnecessary friction in the workflow.

Acceptance Criteria
Provide a "Do not show again" option or a setting preference to permanently disable this specific notification.

Start by reproducing the notification while switching between rooms in the Fat Client on macOS with another room active in the background. Trace the notification and preference handling, then verify that the specific warning can be dismissed permanently and that switching rooms no longer shows it after the choice.

Written by the indexing model from the issue text.