Keep the traffic population and vehicle heights after a globe round trip

The republish after a globe switch ran as a refinement ('Handoff refined'):
it sampled the incoming globe while it still showed coarse tiles and,
being a refinement, never refined again. Keyless Cesium's first terrain
tiles put Austin's streets near -2 200 m, so vehicles stayed there, and
the next globe weighted each road by the camera distance to those
waypoints (1.9 km became 4.1 km), cutting the population from about 620
to 260 until the camera moved.

The handoff is now a completed pass that refines once the incoming
surface has loaded, road density and the coverage radius are measured to
the road's coordinates on the local ground estimate instead of to the
last sampled waypoints, and flow that lands after a publication
re-allocates the retained roads' budgets instead of only recolouring
them.

scripts/format-scope.json

@@ -1040,6 +1040,7 @@
   "src/layers/traffic/roadModes.test.mjs",
   "scripts/qa-traffic-motion.mjs",
   "src/layers/traffic/motion.test.mjs",
+  "src/layers/traffic/handoff.test.mjs",
   "scripts/qa-journey-recorder.mjs",
   "scripts/qa-alpr-journey.mjs",
   "scripts/qa-context-arrivals.mjs",