dsh-tsv: TSV Conversion Plugin

`dsh-tsv` is a dedicated plugin in the DeepSeek Harness (DSH) ecosystem, maintained by `uckkk`. It is a local tool implemented in pure Node.js, focusing on data transformation in the TSV (tab-separated values) format, with no network dependencies. Users can install it using `dsh plugin add github:uckkk/dsh-tsv` and directly invoke its registered tools during DSH sessions to process data. The plugin runs with the permissions of the current process and is suitable for local TSV data processing scenarios.