Move MinIO from minio.localhost to minio.fizzy.localhost, which makes
it same-site with the app, so the CORS redirect succeeds.
The service worker fetches Active Storage URLs with `mode: "cors"` so
it can inspect response sizes for offline caching. Active Storage's
redirect controller returns a 302 to the MinIO presigned URL. When
that redirect crosses site boundaries (from fizzy.localhost to
minio.localhost), the browser sets the Origin header to "null" on the
redirected request per the Fetch spec, which fails the CORS check and
produces net::ERR_FAILED.
Mike Dalessio