🐛(frontend) fix controlbar mobile responsiveness after refactor

Restore proper controlbar layout and spacing on mobile screens that broke
during recent audio control component refactoring, ensuring consistent
user interface across all device sizes.

src/frontend/src/features/rooms/livekit/prefabs/ControlBar/MobileControlBar.tsx

@@ -63,11 +63,13 @@ export function MobileControlBar({
             onDeviceError={(error) =>
               onDeviceError?.({ source: Track.Source.Microphone, error })
             }
+            hideMenu={true}
           />
           <VideoDeviceControl
             onDeviceError={(error) =>
               onDeviceError?.({ source: Track.Source.Camera, error })
             }
+            hideMenu={true}
           />
           <HandToggle />
           <Button