Browsers block ES modules and workers on file:// pages, so the app can't start from a double-click. From this folder run:
file://
npx serve .
then open the printed URL (usually http://localhost:3000). Alternatives: VS Code "Live Server", or python -m http.server 8080.
http://localhost:3000
python -m http.server 8080
A radar cross section sandbox — draw a target, sweep a radar around it, and study the signature. How would you like to start?