dsh-status-plugin: DeepSeek Harness Host Machine Status Monitoring

`dsh-status-plugin` is a standalone client plugin that provides host health monitoring for DeepSeek Harness (DSH). It collects runtime data such as processes, memory, and API key presence through the Host Plane and uses a Web UI with SSE to push real-time alerts and status snapshots, while supporting dynamic threshold adjustments. Installation is simple, the CLI automatically handles configuration, and API keys are only checked for existence to ensure security. This plugin effectively reduces DSH operational troubleshooting costs and is suitable for scenarios requiring real-time monitoring and fault localization.