A stand-in for a hauler's marketing site. Its only job is to host the widget snippet on a
real https origin, because frame-ancestors is enforced by the browser against
the framing page's origin — so the widget cannot be tested from a local file or an
http:// page.
The launcher should appear bottom-right. If nothing renders, check the console: a
frame-ancestors refusal means this page's origin is not on the installation's
allowed_domains, and a 404 on the config fetch means the public key has no
published config at the edge.