Load the Cesium SDK from index.html again, since engine-neutral modules read its global when they load

This reverts ae13a56f. In the production build every 'cesium' import is the global that Cesium.js defines; with the script loaded only when a Cesium globe started, modules evaluated at boot (cesiumConstants, annotationEngine) threw ReferenceError and neither engine started. A cold Navara start loading Cesium.js stays a known gap.

scripts/package-boundaries.json

@@ -1984,7 +1984,6 @@
   "traffic-layer": {
     "exports": ["./layers/traffic"],
     "modules": [
-      "src/layers/shared/color.js",
       "src/data/cameraSensitivity.js",
       "src/data/flowMatch.js",
       "src/data/tomtomTiles.js",
@@ -2658,7 +2657,6 @@
       "src/app/layers/traffic.js",
       "src/app/operations.js",
       "src/app/scene.js",
-      "src/app/loadCesium.js",
       "src/sources/sourceSlot.js",
       "src/app/sources.js",
       "src/app/startupChrome.js",