dsh-plugin-subhub: Integrating Third-Party Subscriptions into DeepSeek Harness

`dsh-plugin-subhub` is an MIT-licensed third-party plugin maintained by `kinoward`, designed to integrate subscription accounts from OpenAI, xAI (Grok), and GitHub Copilot into the DeepSeek Harness (DSH) web interface. This plugin allows users to leverage the model capabilities covered by their existing subscriptions without the need to configure separate API keys. Key features include browser-based authorization login, syncing subscribed models to the model selector, and support for text chat, image understanding, generation, and editing. Users are required to ensure that their Node.js version is above 22.19, and can add the plugin via the command `dsh plugin --profile web add github:kinoward/dsh-plu