dsh-messager: Task Status Notification Plugin for DeepSeek Harness

DSH-Messager is a community notification plugin for DeepSeek Harness, designed to push the agent's session interactions, task completions, and error states to systems, browsers, or third-party platforms. It supports channels such as Feishu, WeCom, Discord, DingTalk, and Telegram, and adopts a single-package dual-end architecture, where the host end handles system notifications and external pushes, and the client end is responsible for browser alerts. Configuration can be edited in real time through the "Notification & Messenger" section of the DSH settings page, or by directly modifying settings.yaml and making RPC calls; the configuration routing is independent of the DSH whitelist. Installation requires building the plugin first, then registering it to the web profile via the `dsh plugin add` command and starting the service. The plugin provides debouncing mechanisms such as deduplication cooldowns and rate limiting.