Implement a node-redis Command

Overview

A command in node-redis is a single Command object exported from packages/<pkg>/lib/commands/<NAME>.ts. It declares how to serialize arguments onto the wire (parseCommand) and how to map the RESP reply to a JS value (transformReply). It becomes callable on clients only after it is registered in the package's commands/index.ts. Both the raw name and a camelCase alias are exposed (HSET and hSet).

This skill is for @redis/client core commands and for module packages (@redis/json, @redis/search, @redis/bloom, @redis/time-series). It does not cover RESP codec changes or new client transports.