Add GPU_FOREIGN_UTIL_PCT: game detection via per-process GPU 3D-engine usage

Reads the same PDH counters as Task Manager (\GPU Engine(*)\Utilization
Percentage, locale-independent via PdhAddEnglishCounterW), which cover
graphics work under WDDM — games are caught without an exe list and the
offender is named. Windows-only; a missing or failing counter disables
the path with one log line. dwm (the desktop compositor) joins the
default ignore list.

cmd/gpu-turnstile/main.go

@@ -592,6 +592,7 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri
 		"comfy_start_timeout", cfg.ComfyStartTimeout,
 		"game_procs", cfg.GameProcs,
 		"gpu_foreign_vram_mb", cfg.GPUForeignVRAMMB,
+		"gpu_foreign_util_pct", cfg.GPUForeignUtilPct,
 		"gpu_ignore_procs", cfg.GPUIgnoreProcs,
 		"game_poll_interval", cfg.GamePollInterval,
 		"auto_update", cfg.AutoUpdate,
@@ -726,13 +727,13 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri
 		go healthLoop(ctx, cfg.HealthInterval, cfg.ProbeTimeout, log, probes, health)
 	}
 
-	// Foreign GPU holders (games, other ML jobs) — enabled by GAME_PROCS
-	// and/or GPU_FOREIGN_VRAM_MB — hold the lock externally while they run.
-	// gw collects the VRAM reading and the last check result for the status
-	// channel.
-	gw := &gpuWatch{enabled: len(cfg.GameProcs) > 0 || cfg.GPUForeignVRAMMB > 0}
+	// Foreign GPU holders (games, other ML jobs) — enabled by GAME_PROCS,
+	// GPU_FOREIGN_VRAM_MB and/or GPU_FOREIGN_UTIL_PCT — hold the lock
+	// externally while they run. gw collects the VRAM reading and the last
+	// check result for the status channel.
+	gw := &gpuWatch{enabled: len(cfg.GameProcs) > 0 || cfg.GPUForeignVRAMMB > 0 || cfg.GPUForeignUtilPct > 0}
 	if gw.enabled {
-		det := game.New(cfg.GameProcs, cfg.GPUForeignVRAMMB, cfg.GPUIgnoreProcs, log)
+		det := game.New(cfg.GameProcs, cfg.GPUForeignVRAMMB, cfg.GPUForeignUtilPct, cfg.GPUIgnoreProcs, log)
 		go gameLoop(ctx, cfg, log, det, lk, ollamaClient, comfySup, gw)
 	}