The favicon was an emoji in a data: URI and /favicon.ico was a 404.
Google only shows a site icon in results when the favicon has a
crawlable URL, and the emoji looked different on every platform.
Add an SVG (a 5x5 card with a crossed-out diagonal), a 16/32/48 ICO
and a 180px apple-touch-icon under assets/bingo/, served by explicit
routes because public/ belongs to asxp.io.
Assisted-by: Claude:opus-5
