dsh-plugin-noticeme: DSH Background Task Notification Plugin

The DSH plugin `dsh-plugin-noticeme` is designed to address issues where agents miss approval or question cards while running in the background because the tab is not visible. It continuously monitors background events and reminds users by triggering desktop notifications or updating the tab title with a "Needs your confirmation" prefix. After installation, browser notification permissions must be granted, and the pending queue is polled every 3 seconds.