dsh-plugin-task-notify: Audio Reminders for Long-Running Tasks in DeepSeek Harness

`dsh-plugin-task-notify` is a DeepSeek Harness plugin designed to address the issue that long-running tasks are easily overlooked. Built on the Web Audio API, it requires no external resources. The plugin plays a “beep” sound when a subtask completes, and a “ding” sound when the full task round times out (default 5 minutes) or finishes. It also supports title bar flashing and TTS announcements. Users can configure the monitoring scope, volume, and announcement templates, ensuring timely feedback during long-running tasks and reducing the risk of missing key milestones.