Move shared follow offsets and Draw onto the globe contract

Share links read the current follow handle and displayed position through
engine.camera and restore their ENU offset with follow's swingTo option.
Cesium retains its first-frame wait, displayed-position cache, 60-degree
frame limit and range interpolation. Navara and the fake engine apply the
same swing. Cancellation, camera handoff and destruction release it; an
externally tracked Cesium entity keeps its existing handle.

Draw uses one surface with engine input, geodesic lines and point movers.
An exclusive pointer claim suppresses ambient subscriptions and deferred
picks across ownership changes. Cesium owns suspension and exact restoration
of its stock select and track actions. Camera gestures remain enabled.
Detaching releases the sketch and preview and retains shape and colour.
The separate Navara surface and Cesium data-source preview are removed.

Cesium remains the reference for clicked heights, line width and dash,
vertex size and outline, keyboard handling and completed annotations.
One deliberate visual fix is that the occluded rubber band uses the selected
colour instead of retaining the initial amber: it now identifies the same
sketch as its visible segment. Navara adopts Cesium's geodesic preview edges.
Finished annotation drapes are unchanged.

External Cesium import files fall from 7 to 5, viewer lines from 1005 to
953, and engine-name lines from 39 to 37. No coupling metric grows.

The full unit suite, import directions, package boundaries, formatting
and coupling checks pass.

Checked in the browser, keyless: the contract suite passes on Navara and on
Cesium apart from the camera-events check that also fails intermittently
before; qa-navara-draw passes; qa-draw-tool passes apart from its hidden-line
pixel check, which fails the same way before this change. Its destroy check
now expects no preview data source, since the preview has none.

docs/CURRENT-STATE.md

@@ -218,6 +218,13 @@ one application, and only the globe-bound parts move to the next engine.
     engines, and `scripts/qa-ground-looks.mjs` drew the jam line and the
     route on Cesium as the old materials did, with no pixel changed at four
     moments of the pulse and the dashes.
+- **Shared follow and Draw.** Share links read the follow target, identity and
+  camera pose through the engine; their saved offset uses `camera.follow`'s
+  `swingTo` option on both engines. Cesium keeps its guarded 60-degree frame
+  swing. Draw uses one contract surface with lines, point movers and an
+  exclusive `engine.input` pointer claim. Cesium's stock select/track actions
+  are suspended by the engine while drawing and restored on release. Scene
+  detach ends the sketch and removes the preview, retaining shape and colour.
 - **Engine-owned effects and camera input.** Cesium's viewer, atmosphere
   compatibility, zoom guard, starry sky and map implementation live in
   `src/globe/cesium/`. Styles, bloom and contact sonar use `engine.render`.