v3.1.1

Fixed

• Editing any setting that shapes the pedestrian graph (Grid Width/Height among them) no longer
  scatters traffic lights across the open scene. The Custom Pedestrians node picker builds a
  throwaway preview of the graph, which instantiates the real Traffic Light Prefab to place its
  crossing nodes; its root was hidden with HideFlags.HideAndDontSave, which hides an object from
  the Hierarchy but still renders it and still registers its colliders. The preview root is now
  inactive and carries its own CityGeneratorRoot, so nothing reaches the scene and
  PedestrianNetwork still scopes its traffic-light matching to the preview itself.
• The same preview no longer cross-matches against a real generated city's intersections when one
  is open in the scene, which added Curb/Crossing nodes to the picker at corners the generated
  city would leave unsignalled.
• A preview root stranded by a domain reload (its owning window's reference is lost, but a
  DontSave object survives) is now destroyed on the next preview build instead of staying in the
  scene forever, invisible in the Hierarchy.