deepseek-harness-jev: Native DSH Plugin for Jev/Luna Decisions Integration

`deepseek-harness-jev` is a native DSH plugin that uses the Jev or Luna Decisions model to provide external assistance for DeepSeek Harness. It does not modify the host source code and integrates through the Cordis API, offering 12 features, including skill/file ranking, task supervision, instruction routing, and log cleanup. All features are disabled by default and must be manually enabled in the configuration page. The plugin is in an early stage, has limited compatibility, and its API judgments carry no correctness guarantees; when installing, ensure DSH version compatibility and manually enable it.