dsh-chat-link: DeepSeek Harness Multi-Session Peer-to-Peer Chat Plugin

The dsh-chat-link plugin provides real-time cross-session communication capabilities for DeepSeek Harness. Users can type `@` in any session to select a target for direct interaction, with support for instant online activation and offline message board delivery. The plugin includes a sidebar inbox UI, five model tools (such as sending messages and viewing lists), and custom linked naming. Data is stored locally with no cloud dependencies. Installation requires Node.js ≥ 22 and can be performed using a one-click or manual script; restart the application afterward to use the plugin.