reuse binary tests for prod builds

It seems vaguely plausible that we could run Cargo's binary tests (`/tests/...`) for production binaries, which would be nice for allowing people to test prod binaries. This is really messy to do on github infra because it doesn't like "staging" releases (draft releases have different URLs from un-drafted ones, so anything that's self-downloading will be confused...), so it may require us to bring up our own infra to do Well.

Start by reviewing the Cargo binary tests under /tests/... and the existing GitHub infrastructure for production or staging releases. Determine whether those tests can run against production binaries without draft-release URL conflicts, and document the infrastructure needed for a reliable end-to-end test path.

Written by the indexing model from the issue text.