dsh-code-security: DeepSeek Harness AI Code Security Review Plugin

`dsh-code-security` is a code security plugin in the DeepSeek Harness ecosystem. It enables code security scanning and policy gating through a deterministic rule engine and incremental review based on git diff. The plugin supports scanning (with CWE/severity evidence), closed-loop remediation verification, policy management, and SARIF/Markdown report export. Installation requires the official command and a compatible Node.js version. It provides a complete solution for Agent pre-delivery security checks, covering the full workflow from incremental review to remediation verification.