Fly, follow and draw the celestial ring through the contract

The Bhote Koshi event flies with engine.camera instead of the viewer's
camera, tools listens to camera.followChanged instead of the viewer's
tracked entity, and the celestial ring uses the engine's host, frames,
pose and render requests. The embedded story media no longer imports
Cesium, which removes one of the three import exceptions.

docs/CODE-BOUNDARIES.md

@@ -100,13 +100,15 @@ panel carries no Navara or three. There is no blanket exception for layer
 
 The temporary `engineImportExceptions` list in `scripts/package-boundaries.json`
 contains exact file/package pairs with reasons. The checker reports the used
-entries and rejects duplicates, missing reasons and unused entries. Its three
-exceptions are the Bhote Koshi event, locator and embedded-media models in
-`src/data/`, which still construct Cesium property records. Their drawing uses
-shared displays. Exceptions do not relax the portable, contract or cross-engine
-graph checks. Cesium annotation renderers live in `src/globe/cesium/annotations/`;
-wind backend adapters live in their engine folders. Wind's older injected-SDK
-helpers and the remaining annotation migration are separate debt.
+entries and rejects duplicates, missing reasons and unused entries. Its two
+exceptions are the Bhote Koshi event and locator models in `src/data/`, which
+still construct Cesium property records. Their drawing uses shared displays.
+Exceptions do not relax the portable, contract or cross-engine graph checks.
+Cesium annotation renderers live in `src/globe/cesium/annotations/`. Wind's
+Cesium rendering (the particle canvas, its GPU path and the relief shading)
+lives in `src/globe/cesium/`; `src/layers/wind/` keeps the data, model,
+presentation and engine-neutral inspection. The remaining annotation migration
+is separate debt.
 
 Source-only factories use dedicated `layers/<family>/source` exports where
 available, preserving the same factory implementation without loading rendering.