feat: scene ghosting, as the client streams a zone's scenes

The client keeps the scene under the player loaded, the scenes the zone
file's transitions connect to it, and the global scene
(Zone::StreamScenesAroundPosition 0x0108a3f0, TerrainManager::GetSceneAtPos
0x01069010, the connected scenes at 0x01066500; transitions naming a
missing scene dropped as Zone::FixupInvalidTransitions 0x010842e0 does).

- ZoneScenes (dCommon): the terrain's scene map lookup and the scene graph,
  shared by the world server and the dashboard.
- Objects remember the scene they were placed in (spawners pass theirs on).
- ghosting_scenes=1 (world config, off by default): players get the objects
  of their loaded scenes instead of the ones within the ghosting distances;
  objects from no scene go by the scene under them. Zones without a scene
  map keep distance ghosting.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDashboardServer/routes/SettingsCatalog.cpp

@@ -150,6 +150,7 @@ namespace {
 		c.Add(Format(Text(SHARED, "dump_folder", "Crash dump folder", "Where crash logs go. Empty turns them off.", "", true), eFormat::PATH));
 		c.Add(Bool(WORLD, "generate_dump", "Crash dumps from world servers", "Write a dump when a world server crashes (needs the crash dump folder).", false, true));
 		c.Add(Bool(WORLD, "save_lxfmls", "Save model files", "Save players' models (LXFML) to disk before they are split, for debugging.", false));
+		c.Add(Bool(WORLD, "ghosting_scenes", "Scene ghosting", "Players get the objects of the scenes their game keeps loaded (the scene under them, the scenes connected to it and the global scene), as the client streams scenes, instead of the ones within 100 to 150 units. Needs the zone's terrain scene map; zones without one keep distance ghosting.", false, true));
 		c.Add(Bool(WORLD, "bbb_consume_bricks", "Brick building uses bricks", "Saving a brick by brick model uses up the bricks in it, as live did. Off: the bricks go back to the backpack.", false));
 		c.Add(Bool(SHARED, "dont_generate_dcf", "Don't build the chat filter file", "Skip compiling the chat word list to a file.", false, true));