Scope pick ownership and selection dispatch to each scene

Create pick registries and selection dispatchers for each scene attachment,
publish them through scene.services, and release their predicates and input
subscriptions before parking the renderer. Resolve layer ownership with the
attached engine so identical layer IDs in simultaneous scenes cannot overwrite
or remove one another. Re-register retained ALPR and cyclone picks on attachment,
and resolve voice pointer picks against the engine that supplied the pick.

Preserve Cesium's selection, sibling ownership, inert trails, touch expansion,
drag and long-press rules on both engines. Extract the unchanged gesture
predicates so portable picking does not acquire a native input dependency.
Exercise scene isolation, teardown and reattachment on fake and headless Cesium
engines, retaining the existing layer assertions.

No coupling count falls or grows. Cesium and Navara renderer lines remain 0 and
189; external Cesium imports 3; viewer lines 910; Navara kind checks 2; engine
sniff calls 0; extension reads 3; ground passes 1; SDK loads 3; screen-handler
files 4; engine-name lines 33.

docs/GLOBE-PRIMITIVES.md

@@ -538,6 +538,15 @@ Cockpit, imagery-box drawing, CCTV calibration and infrastructure flights use
 these methods on every engine. Pointer claims remain separate from camera
 input suspension.
 
+Pick ownership belongs to the scene attachment, not to an engine implementation.
+`scene.services.picking` owns its predicates and `scene.services.selection` owns
+its shared click dispatcher. Layer entry points resolve these services using
+their attached engine (`sceneServicesFor(engine)`); the pick-registry helper
+functions take that engine as their final argument. Standalone entries acquire
+the same services on first use. The application destroys them on detach and
+creates fresh services when reattaching a parked engine. Identical layer IDs in
+simultaneous scenes cannot replace or unregister one another's picks.
+
 ## Render effects
 
 The optional `visualStyles`, `bloom` and `contactSonar` capabilities are