Merge origin/main into german/navara

Main's camera, voice, Cockpit and layer work now runs on the globe
contract where this branch draws through it:

- The voice tilt to an angle, its pivot about the place under the
  crosshair and the frame limit from orbit run through the camera rig;
  src/globeInView.js measures a camera pose with src/geo instead of a
  Cesium camera. The free-look height limit and the globe-in-view
  recovery stay Cesium-only for now.
- Cockpit takes main's own-layer entry rule. Double-clicking the
  followed track goes through cockpitHost.routeDoubleClick, so it works
  on both engines.
- Space Missions' failed-entry rollback and GhostMaps' age filter run
  in the engine-neutral layer code. On Cesium an expired report is
  dropped in place; on Navara its product is redrawn.
- Wildlife Sightings joins the catalog Cesium-only: Navara leaves it
  out, and the shell builds its card only for the real layer, so a
  Navara page no longer fails to start on its stand-in.
- One instruction sentence is shorter, which keeps the Realtime prompt
  within its 55,500-character budget with the Sentinel-2 basemap.

scripts/run-unit-tests.mjs

@@ -1,4 +1,4 @@
-import { readdirSync } from 'node:fs';
+import { existsSync, readdirSync } from 'node:fs';
 import { spawnSync } from 'node:child_process';
 import path from 'node:path';
 import { pathToFileURL } from 'node:url';
@@ -45,7 +45,10 @@ export function discoverUnitTestFiles(root = process.cwd()) {
       }
     }
   };
-  for (const testRoot of UNIT_TEST_ROOTS) visit(path.join(root, testRoot));
+  // A checkout without one of the roots (a test fixture) has no tests there.
+  for (const testRoot of UNIT_TEST_ROOTS)
+    if (existsSync(path.join(root, testRoot)))
+      visit(path.join(root, testRoot));
   return files.sort();
 }