Preload lifecycle

// Root — client only
<PoseTrackerProvider>
  <Navigation />
</PoseTrackerProvider>

// Lobby — model warm-up, no permission prompt
function HomeScreen() {
  const { preload, status } = usePoseTracker();

  useEffect(() => {
    void preload(); // basic, idempotent
  }, [preload]);

  return (
    <>
      <View style={{ width: 1, height: 1, opacity: 0 }} pointerEvents="none">
        <WebViewPoseView coldStart="basic" />
      </View>
      <Button title="Start" disabled={status !== 'ready'} onPress={goToCamera} />
    </>
  );
}

// Camera — user expects the permission prompt
function CameraScreen() {
  return <WebViewPoseView style={{ flex: 1 }} />; // coldStart="full"
}