DeepSeek Harness Code Review Plugin

`dsh-plugin-code-review` is a structured code review plugin designed for DeepSeek Harness to enhance an agent's review capabilities. It teaches systematic review steps covering correctness, security, performance, style, and testing, helping agents identify logic errors, security vulnerabilities, and coding issues. Users can integrate the plugin into DSH with an installation command and then simply issue a review request in the chat. The agent will then automatically generate results with severity labels, helping developers quickly pinpoint issues.