Cut duplicated and dead code across the engines, the layers and the QA scripts

- src/geo drops the ported debug argument checks and the tests that
  bitExact already covers; package boundaries accept a directory entry,
  so src/geo/ is listed once per group.
- Cesium no longer carries movers and lines nobody draws with: they are
  optional engine capabilities. The fake engine and the Cesium camera use
  the shared cameraMath; unused contract tables, clock.ticked, the
  'finest' surface detail and Navara click statistics are gone.
- ALPR keeps one overlay core and one presentation model for both
  engines, bikeshare one station bookkeeping, the Navara ground effects
  one definition helper; image atlases, view centres, mover banks and
  colours are shared.
- The legacy switch route, the clock offset and rate controls and other
  unused exports are removed.
- The acceptance runs the Navara draw, geo import and scope checks;
  scenarios use the harness switch and page helpers; the main chunk
  check keeps the size budget only and runs once in CI.

scripts/check-import-directions.mjs

@@ -30,9 +30,9 @@ const globeEngine = (file) => /^src\/globe\/(?:cesium|navara)\//.test(file);
 const cesiumPackage = /^(?:cesium(?:\/|$)|@cesium\/)/;
 // Navara renders through three.js and its postprocessing peer.
 const navaraPackage = /^(?:(?:three|postprocessing)(?:\/|$)|@navaramap\/)/;
-// Phase 3: the layers moved onto layer renderers (the *a tasks) keep each
-// engine in their renderers: cesium only in render/cesium*.js, three and
-// Navara only in render/navara*.js. The list grows with each moved layer.
+// Layers built on layer renderers keep each engine in their renderers:
+// cesium only in render/cesium*.js, three and Navara only in
+// render/navara*.js. The list grows with each layer moved onto renderers.
 const RENDERED_LAYER_DIRS = [
   'src/layers/alpr/',
   'src/layers/airQuality/',