Remove always-true layer availability and leftover viewer paths

Every layer draws on both engines, so the per-engine availability
machinery always answered yes. The renderer manifest is now the id to
display map plus the wind flow backend; the catalog filter, the voice and
QA-probe refusals and the engine-kind checks go with it. The Navara
notice lists the same layers in the same words.

Paths that read the Cesium viewer behind an engine that is always there
are gone: the Recent Imagery viewer fallbacks, the shell's imagery-host
service (one shared host module remains), the engineless map controller,
viewer gates in voice actions, world packets and camera verbs, the
orientation controls' tracked-entity fallback, and the Bhote Koshi and
FIRMS Cesium-shaped paths. setCameraInputs, which nothing called, leaves
the contract; suspensions remain.

Smaller duplicates go too: one tracker-release helper for navigation and
location, the no-op frame latch, missing-engine guards, one name for the
injected display, flat bikeshare and installations displays, one overlay
host and binder, one name per world-overlay method, and stub-viewer
guards in the Cesium engine. Layers that still read the viewer keep the
shared init(viewer, context) entry.

Behaviour is unchanged on both engines. Viewer lines fall from 849 to
750 and engine-name literals from 32 to 27.

docs/GLOBE-PRIMITIVES.md

@@ -331,7 +331,7 @@ On the engine:
 
 - on the globe's imagery layers while the globe shows, else on the shown 3D
   tileset's own imagery layers (Cesium drapes imagery on tiles there), as
-  `src/maps/imageryHost.js` resolves it for the shell; with neither, the
+  `engine.imagery.surface()` reports it to layers; with neither, the
   layers wait;
 - the engine checks the surface on every frame while it holds a layer, and
   builds each layer again on the new stack after a switch;
@@ -474,8 +474,7 @@ against the native ellipsoidal occluder, including points near the limb.
 `engine.input.suspendCameraInputs()` disables camera gestures and returns an
 idempotent resume function. Suspensions are counted: only the last resume
 restores the state captured before the first suspension. This preserves an
-already-disabled camera. A `setCameraInputs()` call during suspension updates
-the state restored on resume. `cameraInputsEnabled()` reads the current state.
+already-disabled camera. `cameraInputsEnabled()` reads the current state.
 Cockpit, imagery-box drawing, CCTV calibration and infrastructure flights use
 these methods on every engine. Pointer claims remain separate from camera
 input suspension.
@@ -539,7 +538,7 @@ Positions stay live cached visual anchors. `trackedReadoutFor(engine)` resolves
 the service; destruction removes its listeners and clears only its own source.
 
 `scene.services.context` owns selection records and notifications. Layer publishers
-use `bindContextStore` with their current engine, or a context service captured by
+use `bindOverlayHost` with their current engine, or a context service captured by
 their display. It mirrors records to the page context slot and preserves the
 `gev:entity-selected`, `gev:entity-selection-cleared` and aircraft awareness event
 payloads for page consumers. A clear reaches the page only when that attachment