network-manager-gnome autostarts its own systray icon from /etc/xdg/autostart,
which duplicates the network genmon (plugin-13) already in the panel. Override
it with a Hidden=true user-level .desktop, the same way blueman-applet and
nm-tray are already handled, and copy it into place from the panel installer.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>