dsh-water-electrolyte: Accurately Calculate Sweat Electrolytes Based on Parameters

The `dsh-water-electrolyte` plugin released by DeepSeek Harness (DSH) is designed to address sweat electrolyte calculation needs within sessions. It provides precise calculations and clear recommendations, is implemented purely in Node.js, and has no network dependencies. Developers can install it via a command, and it runs with the permissions of the current process. Note that, as it involves health-related calculations, the recommendations are for reference only; for medical advice, please follow a doctor's instructions.