Let a shell without its navigation owner report no camera handoffs

The voice runner subscribes to camera handoffs as it is created. The Cyber sonar test builds its runner on a StyleManager made from the prototype, which has no navigation owner, so the facade's delegation threw and both Node jobs failed. The facade now returns nothing there, like its other optional owners; the real shell builds its navigation owner before voice creates a runner.

scripts/format-scope.json

@@ -1128,6 +1128,7 @@
   "src/dockerTrustedPeers.test.mjs",
   "src/cameraGlobeRotation.test.mjs",
   "src/cameraTilt.test.mjs",
+  "src/ui/shellFacade.test.mjs",
   "src/voice/globeResetConfirmation.test.mjs",
   "src/hudDms.test.mjs",
   "src/hudSummaryGate.test.mjs",