UFace XMP WebAssembly

Pick a carrier JPEG and an embedded JPEG. The browser will call the shared C encoder through WebAssembly, post the base64 JPEG to the validation API from `server/README.md`, and show the mapped response model.

Use `/api/validate` when this page is served from the same origin as the API. If you use a different host or port, the browser also needs CORS permission from the validation server.

Ready.
No encrypted upload has been created yet.
No validation response yet.