Add livemedia-creator --make-iso pipeline that produces a small
Anaconda installer ISO consuming a CI-buildable variant of the
runtime ostreecontainer kickstart. Disk/LUKS/user blocks dropped
from the CI ks (Anaconda interactive handles them); ostreecontainer
URL pinned to ghcr.io/veilor-org/veilor-os:43. Output split into
1900M chunks; published to Forgejo installer-latest rolling tag.
