dsh-multi-model-provider: Model Catalog, Profile Construction, and Agent Model Selection

`dsh-multi-model-provider` is a core plugin of DeepSeek Harness (DSH), designed to manage the multi-model ecosystem in a unified way. Its core features include model registration, evidence-based profile construction, and primary model selection for Agents. Developers can inject `modelCatalog` to retrieve the model list and dynamically select models, while also using command-line tools to manage model routing and non-language models. Providers such as Volcano Engine Ark can be configured in the settings interface. Note that the plugin only manages catalogs and logic, does not directly invoke image or speech models, and emphasizes metadata authenticity and security.