dsh-fatigue: Fatigue Self-Assessment Plugin

`dsh-fatigue` is a lightweight home health self-check plugin for DeepSeek Harness (DSH). It can be integrated with simple configuration, requires no network requests, and supports running fatigue self-assessments locally to return results. Built with pure Node.js and depending on the DSH core library, it is well suited for integrating health self-check logic in offline environments.