fix(lint): suppress gosec G404 for demo data RNG

vhs/backfill/main.go

@@ -28,7 +28,7 @@ func main() {
 		os.Exit(1)
 	}
 
-	rng := rand.New(rand.NewPCG(42, 0))
+	rng := rand.New(rand.NewPCG(42, 0)) //nolint:gosec // deterministic seed for reproducible demo data
 	now := time.Now().UTC()
 
 	if err := backfillHistory(db, rng, now, ids); err != nil {