Add scripts/gamemode-watch.py, launched at niri startup, which subscribes
to niri's event stream and toggles gamemode whenever a game window
(steam_app_*, RuneLite, gamescope) is open — so Steam games trigger
gamemode with zero per-game setup instead of needing gamemoderun %command%.
'winwatch' is a third reference-counted source alongside feral + manual.
Pure Watcher class is unit-tested; SIGTERM/finally guarantee cleanup so
the watcher stopping never leaves gamemode stuck on.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
funman300