dsh-negotiation: Scenario-Based Structured Negotiation Strategies

The `dsh-negotiation` plugin for DeepSeek Harness is maintained by uckkk and aims to provide standardized, structured strategies and recommendations for negotiation scenarios in model inference and agent development. Implemented in pure Node.js with no network dependencies, it addresses the challenge of maintaining prompt logic. Users can install it via the CLI and directly invoke the `negotiation` tool within a session to obtain the corresponding negotiation methods. This tool is suitable for various tasks that require handling negotiation logic.