A reboot before the first deploy would leave the enabled unit in failed
state; the condition keeps it inert until start.sh exists (same guard as
nexus-worker.service).
- new install/nexus-runtime.sh (idempotent, re-runnable on an existing
LXC): uv for the nexus user (manages Python 3.12), tesseract deu+eng,
nexus-worker.service unit (ConditionPathExists guards the skeleton
phase), sudoers extended to cover the worker service
- nexus-install.sh: RUNTIME section now invokes nexus-runtime.sh at the
end of the install (after base sudoers/units, which it extends)
l.kirchner