docs: specify LoopSpine skill spine rollout

[uncfreak1255-code]

Summary

• define one-repository ownership with the skill as engine and plugin as delivery
• keep pilot use explicit and local until ten real tasks pass
• require evidence before hooks, global adoption, or reusable role definitions
• specify pilot task mix, proof metrics, promotion gate, and rollback

Proof

• npm test
• autoreview clean: no accepted/actionable findings