Reverse the skill location: the full definitions now live in
.opencode/skills/<name>/SKILL.md (opencode's native project-skill
location, auto-scanned), and .claude/skills/<name>/SKILL.md are thin
pointer wrappers that keep the frontmatter for discoverability and
redirect to the .opencode/ canonical file for the procedure.
Also drops the 'operator-authorized mid-run' gating from
/cc-ci-server-update: the operator's choice to invoke the skill IS the
authorization for the live nixos-rebuild switch — no second check to
wait for. The quiescent-moment preference stays (don't disrupt an
in-flight !testme), but it's not a gate.
