dsh-factory-provider: Integrate Factory Subscription Credits into DeepSeek Harness

`dsh-factory-provider` is an open-source plugin designed to integrate Factory (Droid) models into the native environment of DeepSeek Harness (DSH). It allows users to use Factory API keys directly for inference in DSH. The plugin supports multi-model grouping, upstream failover, secure local API key storage, token usage statistics, and subscription quota monitoring. Installation requires adding it via CLI and restarting DSH, with Node.js >= 20 and DSH version 0.2.0-rc.2 or later.