dsh-peer-relay: DSH Host-Side Peer Session Relay Tool

`dsh-peer-relay` is a host-only plugin for DeepSeek Harness (DSH), designed to enable two independent agents to collaborate as peers. The plugin provides five core tools that allow developers to create, manage, invoke, and monitor peer sessions within the same workspace, supporting bidirectional asynchronous task delivery and result retrieval. It relies on SQLite for state storage and is strictly scoped to a single workspace. This tool offers developers a lightweight, direct session communication solution, suitable for scenarios where multiple agents need to handle tasks for the same project in parallel.