Slide-out panel with brightness, volume, Wi-Fi, Bluetooth,
and airplane mode. Fully gamepad-navigable; D-pad and stick
input routed to the panel while open. System status bar
(clock, battery, connectivity) added to game center header.
Lutris games discovered from ~/.local/share/lutris/pga.db,
Heroic from ~/.config/heroic/store_cache/ JSON files.
Deduplication extended to cover all launcher sources.
Desktop entries launched via KIO::ApplicationLauncherJob to
expand Exec field codes. Generic commands parsed with
KShell::splitArgs. SQLite uses RAII cleanup guard.
Clamped SDL axis, rumble, and LED values. Renamed rumble
params from frequency to intensity. GamepadManager uses
singleton factory. setPlayerIndex checks SDL return.
FavouritesBar popup uses screen virtualX/Y for multi-monitor.
