review-gate: DeepSeek Harness Hard Code Review Gate Plugin

`review-gate` is a DeepSeek Harness plugin designed to turn code review into a hard gate. It uses deterministic static rules and optional LLM assistance to classify code issue severity, and combines a team voting mechanism to block non-compliant merge operations. The plugin supports audit log tracking, CI integration, and reuse of a lessons-learned library, ensuring code quality compliance for teams with high security requirements.