Refine ship orders and viewer controls

apps/backend/Definitions/WorldDefinitions.cs

@@ -559,6 +559,9 @@ public sealed class ShipCargoDefinition
 public sealed class ScenarioDefinition
 {
     public required WorldGenerationOptions WorldGeneration { get; set; }
+    // Temporary QA escape hatch so a scenario can pin an exact topology.
+    // Do not treat this as the long-term world authoring model.
+    public List<SolarSystemDefinition>? Systems { get; set; }
     public required List<InitialStationDefinition> InitialStations { get; set; }
     public required List<ShipFormationDefinition> ShipFormations { get; set; }
     public required List<PatrolRouteDefinition> PatrolRoutes { get; set; }