version is now settable via -ldflags -X for tagged builds instead of a
hardcoded "dev" string.
.github/workflows/release.yml cross-compiles linux/amd64 and linux/arm64
binaries on tag push (or manual dispatch), and publishes them to a GitHub
Release with checksums - the artifact packaging (Nivora's Staplerfile,
`go install`) is expected to consume from there.
