Stop Navara's memory growth on engine switches, hide polygon zones reliably, and drop the Cesium camera rig

- Navara 0.2.1 never frees pick batch ids, and the mover banks rebuilt
  their instanced meshes on each attach, leaking about 260 KiB of
  WebAssembly memory per switch. A per-view pool hands released ids back
  out; the long soak now asserts native growth of at most 32 KiB per switch.
- Navara 0.2.1 sometimes drops the first show:false update on a new
  vector layer, so a zone turned off right after a switch back stayed
  drawn. Polygon displays hide by deleting their layers and rebuild them
  when shown.
- Camera verbs drive both engines through the globe contract; the Cesium
  viewer rig and the tests of states it can no longer reach are gone.
- Flights and military tracking share src/layers/aircraft/tracking.js.
- The geo import scenario reads movers only where the engine has them.
- Add the Navara section to docs/CURRENT-STATE.md and a changelog fragment.

scripts/format-scope.json

@@ -368,8 +368,10 @@
   "src/layers/military/index.js",
   "src/layers/aircraft/index.js",
   "src/layers/aircraft/classification.js",
+  "src/layers/aircraft/tracking.js",
   "src/layers/military/ownership.test.mjs",
   "src/layers/aircraft/classification.test.mjs",
+  "src/layers/aircraft/tracking.test.mjs",
   "src/data/aisLiveVessels.js",
   "src/layers/vessels/cards.js",
   "src/layers/vessels/evidence.js",
@@ -1297,6 +1299,7 @@
   "src/globe/cesium/engineFromViewer.js",
   "src/globe/cesium/engineFromViewer.test.mjs",
   "src/globe/cesium/testing/fakeViewer.mjs",
+  "src/globe/cesium/testing/cameraViewer.mjs",
   "src/app/globeEngine.js",
   "src/app/globeEngine.test.mjs",
   "src/layers/transit/render/cesium.js",