dsh-plugin-discord: Connect DeepSeek Harness sessions to Discord

dsh-plugin-discord is a Discord bridging plugin for DeepSeek Harness (dsh), allowing users to share the same batch of dsh sessions with the Web UI within Discord. The plugin integrates Discord messages from whitelisted users into dsh and returns replies, while also supporting proactive notifications pushed via HTTP API and MCP endpoints. Core features include registering slash commands (such as /new, /sessions, /stop, etc.), inline rendering of the ask_user_question interaction component in Discord (requires dsh >= 0.1.1), and file transfer via specific tags (Agent sends files to Discord).