Add layered system viewer and local coordinates

apps/backend/Simulation/SimulationEngine.cs

@@ -77,7 +77,7 @@ public sealed class SimulationEngine
       world.Nodes.Select(ToNodeDelta).Select((node) => new ResourceNodeSnapshot(
         node.Id,
         node.SystemId,
-        node.Position,
+        node.LocalPosition,
         node.SourceKind,
         node.OreRemaining,
         node.MaxOre,
@@ -87,7 +87,7 @@ public sealed class SimulationEngine
         station.Label,
         station.Category,
         station.SystemId,
-        station.Position,
+        station.LocalPosition,
         station.Color,
         station.DockedShips,
         station.OreStored,
@@ -99,9 +99,9 @@ public sealed class SimulationEngine
         ship.Role,
         ship.ShipClass,
         ship.SystemId,
-        ship.Position,
-        ship.Velocity,
-        ship.TargetPosition,
+        ship.LocalPosition,
+        ship.LocalVelocity,
+        ship.TargetLocalPosition,
         ship.State,
         ship.OrderKind,
         ship.DefaultBehaviorKind,