go.sum was never committed (no local Go toolchain to generate it),
causing "missing go.sum entry" build failures on target hosts.
go mod tidy regenerates it automatically before go build.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
/usr/local/bin wasn't guaranteed to be on PATH in non-interactive
shells, so the symlinked go binary was invisible to later steps.
Export PATH explicitly and fail fast if go is still missing.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
