dsh-mandarin-grade: Mandarin Grade Calculation

dsh-mandarin-grade is a pure Node.js plugin for DeepSeek Harness (DSH) that calculates Mandarin grades locally without network dependencies. The plugin registers the `mandarin_grade` tool, supports precise calculation based on parameters, and returns detailed results. Installation must meet the version requirements for `@deepseek-ai/cordis` and `@deepseek-ai/dsh-tools`, and can be performed using the official command. After installation, users can invoke the tool directly within a conversation. Since the plugin runs with DSH process privileges, please check the source code and license before use.