yhyfhgs/dsh-model-hub: DeepSeek Harness Unified Model Management Plugin

The `yhyfhgs/dsh-model-hub` plugin aims to address fragmented model management in DeepSeek Harness (DSH) by unifying the local loopback `/model-hub` RPC channel to centrally provide model login, catalog management, session routing, and configuration. It supports OAuth login, model customization, inference effort control, and a bilingual interface, and includes multiple built-in providers. Installation requires the `dsh plugin` command and a profile restart. The configuration is strictly bound to the local loopback address to ensure security.