deepseek-harness-dingtalk: DingTalk Stream Channel Plugin for DeepSeek Harness

`deepseek-harness-dingtalk` is an MIT-licensed DingTalk channel plugin designed to integrate DeepSeek Harness (DSH) agents with DingTalk. Leveraging the official Stream WebSocket connection, this plugin eliminates the need for a public network callback server and requires only the configuration of a Client ID and Secret to establish the connection. In terms of core capabilities, the plugin supports receiving text, Markdown, rich text, speech-to-text, images, and standard files, while securely handling media downloads and multimodal inputs via the official API. On the output side, it supports DingTalk native Markdown replies, images, and workspace file uploads, and can fully execute the Harness Agent Loop. The plugin provides in-session tool approval (via one-time codes),