dsh-combination: Combination Counting Plugin

The `dsh-combination` plugin for DeepSeek Harness (DSH) is used to handle combinatorial logic in inference workflows. Maintained by uckkk, it is built with pure Node.js, has no network dependencies, and is suitable for offline environments. Installation requires satisfying the version requirements of `@deepseek-ai/cordis` and `@deepseek-ai/dsh-tools`, and the plugin must run with process-level privileges.