A builder droplet starts with no images, so publish.yml built
omarchy-pkg-builder from the Dockerfile each time: about 100 s of
pacstrap, keyring setup and toolchain install, to run gpg, repo-add,
bsdtar and rclone for about 14 s.
builder-images.yml already publishes the tested image for the current
build inputs to ghcr.io/omacom/omarchy-pkg-builder under bin/builder-image
key. Pull that, check its org.omarchy.builder.key label, and tag it as the
local name the rest of the step uses.
Build as before when no image carries the key, which is what a merge
that changes build/ sees until the refresh it triggered has finished.
Co-authored-by: Ryan Hughes <ryan@heyoodle.com>
