Send mention alerts from task comments to assignees

You miss task comment mentions and assignees lack context, causing blocked work and delayed deliverables. Notifications go to the right people so issues are triaged quickly within minutes.

Overview

When people are mentioned in task comments, work stalls if those mentions go unseen; this routes mention alerts directly to the right people. It turns buried comments into immediate, actionable DMs so triage happens within minutes and blockers get resolved ahead of deadlines.