Move the engine switch protocol from the layers into the scene binding

attachRenderer takes one context { engine, signal, viewRestored, ... } and
bindCatalog no longer takes a viewer; no layer module receives Cesium's
viewer any more, and a rehearsal check fails if one reads it.

The handoff between engines is one typed object (layers, camera owners,
selection, director) created when the old scene leaves, replacing the
session's handoffLayers, restoringView and selectionContext. viewRestored
resolves where the camera is restored, and the nine layers that kept
their own restoring-view flag wait on it instead. After attach the
binding applies a disabled layer's visibility, registers the picks each
module declares, and resumes the camera owners, so engineSwitch.js no
longer names directions or satellites.

src/app/layers/displayRehearsal.test.mjs

@@ -256,7 +256,7 @@ const cases = {
         return make(value);
       },
     });
-    layer.attachRenderer(null, { engine });
+    layer.attachRenderer({ engine });
     const renderer = context.parts.renderer;
     const station = {
       id: '00000000-0000-4000-8000-000000000000',