dsh-plugin-repo: Self-Hosted Plugin Repository for DeepSeek Harness

`dsh-plugin-repo` is a self-hosted plugin repository that runs on top of DeepSeek Harness (DSH). As a pure Cordis plugin, it provides an HTTP service for listing, uploading, and downloading plugins, and supports cross-device synchronization and version-aware installation. Built-in protection mechanisms ensure that official core packages are not modified, while also offering a RESTful API and a settings interface. Users can install it via npm and use its configuration directory to manage local plugins, enabling secure and controllable plugin distribution and maintenance.