feat(skill): implement multi-agent-mux-orc-onboard skill and orchestrator_uuids exclusion gate (40/40 PASS)

deploy/gitea-ci.yml

@@ -35,6 +35,7 @@ jobs:
           shellcheck .agents/skills/multi-agent-mux-loop/scripts/run_loop.sh
           shellcheck .agents/skills/multi-agent-mux-loop/scripts/diff_collect.sh
           shellcheck .agents/skills/multi-agent-mux-loop/scripts/loop_lock.sh
+          shellcheck .agents/skills/multi-agent-mux-orc-onboard/scripts/orc_onboard.sh
           shellcheck .agents/hooks/loop_delegation_guard.sh
           shellcheck deploy/lib_ownership.sh
           shellcheck deploy/install.sh