dsh-sleep-hygiene: A Local Sleep Hygiene Advisory Tool

The `dsh-sleep-hygiene` plugin for DeepSeek Harness (DSH) is maintained by developer uckkk and implemented in pure Node.js. It registers a `sleep_hygiene` tool that generates sleep-hygiene recommendations locally based on the provided parameters, without making any network calls. After installation, it can be used directly by invoking it in a session. It is suitable for lightweight, network-independent sleep-guidance scenarios, but the generated recommendations are for reference only.