DSH-Skin-Manager: Skins Manager for DSH Web GUI

`dsh-skin-manager` is a lightweight skin management plugin for the DeepSeek Harness Web GUI, maintained by `xiaoyangcheng84-svg` and released under the MIT license. This plugin aims to address the tedious issues of state management and switching when multiple skin packages coexist, consolidating skin discovery, activation, mutual exclusion, and default restoration into the settings page. Its core features include dynamically discovering installed skins with `skin.json` or marketplace themes, providing a dedicated `Settings → Skins` settings page, supporting one-click application and hot updates, ensuring only one skin is active at a time, and allowing restoration of the default appearance at any time. Additionally, it integrates with `dsh-market` to synchronize state files and clean up conflicting mounts, preventing state conflicts during startup.