dsh-plugin-auth-guard: Adding a layer of Zero Trust authentication and access control to DeepSeek Harness

# Preface DeepSeek Harness (DSH) is an AI coding agent runtime designed for local desktop workflows, defaulting to 127.0.0.1. Once you attempt to expose it to mobile devices on a local area network (LAN) or deploy it to a cloud server, you will encounter several obstacles: 1. Calls to privileged interfaces (e.g., `settings.describe`, `llm.providers`) from non-localhost sources are blocked with 403 Forbidden, making remote model switching impossible; 2. Mobile browsers lack a Secure Context in a pure HTTP environment, resulting in `crypto.randomUUID` being undefined, and RPC...