dsh-github-router: Introduction to the DeepSeek Harness Plugin

`dsh-github-router` is an open-source plugin for DeepSeek Harness, designed to address network issues when accessing GitHub in sandboxed environments. It encapsulates routing logic and provides structured tools such as `github_pr`, `github_issue`, and `github_file`, supporting multiple access methods including API, CLI, and Git protocol. The plugin offers read-only capabilities only, supports configuring a token to increase rate limits, and is an ideal choice for agents that need to retrieve GitHub data.