dsh-model-health: DSH Model Availability and Latency Testing Plugin

The `dsh-model-health` plugin for DeepSeek Harness (DSH) is used to manage the availability and performance of multi-model configurations. It provides a Web UI panel to display model details and supports concurrent testing of all models (up to 6 models, with a 10-second timeout), with results stored persistently. Additionally, the plugin provides a `list_models` tool for viewing the model list during a conversation. Installation requires specifying dependency versions.