dsh-llm-grok: LLM Provider for Integrating Grok Subscriptions into DeepSeek Harness

`dsh-llm-grok` is a DeepSeek Harness (DSH) plugin intended to integrate X.AI's Grok subscription into the DSH ecosystem. It supports native multimodal capabilities, multiple reasoning effort levels, and HTTP proxying. Installation is performed by adding it through the command line, and it depends on a `GROK_SESSION_TOKEN` that must be manually maintained by the user. The plugin does not support automatic token renewal; the token must be synchronized every 5 minutes via a script or environment variable. Additionally, it implements only the `chat-completions` endpoint and has specific limitations in image processing.