"Etcd"
- etcd → Consul：KV + N 個 extras feature matrix etcd → Consul 是 Type E paradigm shift expansion — 從 pure KV store 升到 service mesh / discovery / health check / multi-DC；本文用對照表 + paradigm expansion 路線、5 個 production 踩雷（API 對位 / lock semantics / watch event model / multi-DC topology / ACL system）