Isolate legacy range-expansion factor

scripts/run_backtest_snapshot.py

@@ -56,6 +56,7 @@ def _parse_args() -> argparse.Namespace:
             "legacy_geometry_neutral", "legacy_pivots_only",
             "legacy_traffic_grid_only", "legacy_range_grid_touch",
             "legacy_range_grid_neutral",
+            "production_range504", "rewrite_range504_legacy_primary",
         ),
         default=None,
         help="Research-only S/R detector/gate arm.",