feat(globe): implement the engine on Cesium

createCesiumEngine wraps an existing viewer without changing it: camera, picker, projector, frames, render (through the render governor), surface, input, credits and maps, with geo values out and Cesium values in at the boundary. Map and surface code is shared with src/maps and services/groundSnap instead of copied. scripts/qa-globe-contract.mjs runs the contract suite against the engine in headless Chrome; the camera-events check now waits for the previous move to end, as Cesium's moveStart marks a move from rest.

src/globe/cesium/frames.js

@@ -0,0 +1,29 @@
+// Frame events on a Cesium scene. Listeners receive the frame's scene time
+// as Unix milliseconds.
+
+import * as Cesium from 'cesium';
+import { bridgeEvent } from './events.js';
+
+const toMilliseconds = (scene, time) => [
+  Cesium.JulianDate.toDate(time).getTime(),
+];
+
+/**
+ * @param {Cesium.Viewer} viewer
+ * @returns {{ frames: object, destroy: () => void }}
+ */
+export function createCesiumFrames(viewer) {
+  const { scene } = viewer;
+  const bridges = ['preUpdate', 'preRender', 'postRender'].map((name) => [
+    name,
+    bridgeEvent(scene[name], toMilliseconds),
+  ]);
+  return {
+    frames: Object.fromEntries(
+      bridges.map(([name, bridge]) => [name, bridge.event]),
+    ),
+    destroy() {
+      for (const [, bridge] of bridges) bridge.detach();
+    },
+  };
+}