dsh-llm-opencode: DeepSeek Harness's OpenCode Zen Free Model Adapter

`dsh-llm-opencode` is an MIT-licensed DeepSeek Harness (DSH) plugin developed by bobowsh, designed to integrate OpenCode Zen providers into DSH. By registering the `opencode-zen` route, the plugin converts DSH requests into the OpenAI-compatible chat completions format and supports parsing SSE stream responses. Its core advantage is that it supports OpenCode Zen's free models, enabling users to utilize them directly without configuring an API key; for paid models, API keys can be configured via environment variables or credentials. The plugin features a built-in directory of free models and automatically synchronizes the latest model list from the gateway and models.dev in the background.