The k8up CLI (`k8up cli restore`) has no package, so restores need a manual GitHub download on each host.
- add k8up package pinned to 2.16.0, matching the deployed operator
- verify the release tarball against upstream checksums.txt
- ship urfave/cli bash, zsh and fish completions
- build for el9 and fedora 42-44
Requires terraform-artifactapi github allowlist for k8up-io/k8up.
Reviewed-on: #181
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
