Add Visual, Reasoning Tier and Token Capacity for Custom Models in DeepSeek Harness via better-model-provider

### 正式翻译： The official "Models" page of DeepSeek Harness can manage providers and API keys, but in the past, adjusting the inference strength levels, visual input capabilities, and token capacity for custom models could only be done by manually editing the YAML files. The MIT-licensed plugin `better-model-provider` maintained by sanshanya added a "Model Capabilities" section on the settings page, which configures these native capabilities based on the model's declared specifications, without modifying the Harness runtime or touching credentials. This article verifies the installation commands, usage methods, and compatibility boundaries based on the community directory page and the GitHub README.