Tasks: Notification templates for pause/resume #1260

Repo: coder/coder

Scope: Add notification templates so users are notified when their tasks pause or resume.

Changes:

• Add TemplateTaskPaused UUID to coderd/notifications/events.go
• Add TemplateTaskResumed UUID to coderd/notifications/events.go
• Create notification template files with appropriate messaging
• Trigger TemplateTaskPaused from pause code paths (auto and manual)
• Trigger TemplateTaskResumed from resume code path

Template variables (suggested, follow existing notification patterns in coderd/notifications/templates/):

• TaskName: Name of the task
• TaskURL: Direct link to task page
• WorkspaceName: Underlying workspace name
• PauseReason: "idle timeout" or "manual" (for pause notification)
• UserName: Task owner's username

Note: Review existing task notification templates (TemplateTaskWorking, TemplateTaskIdle, etc.) for consistent variable naming.

Trigger points:

• Auto-pause: Lifecycle executor when stopping workspace with task_auto_pause reason
• Manual pause: POST /tasks/{task}/pause endpoint handler
• Resume: POST /tasks/{task}/resume endpoint handler

Files:

• coderd/notifications/events.go
• coderd/notifications/templates/ (new templates)
• coderd/autobuild/lifecycle_executor.go (auto-pause trigger)
• coderd/aitasks.go (manual pause/resume triggers)

Acceptance criteria:

• User notified when task is paused (auto or manual)
• User notified when task is resumed
• Notifications work via email and webhook delivery methods
• Notification content distinguishes auto vs manual pause
• Task URL in notification links directly to task page

Dependencies:

• Tasks: Database migrations for task lifecycle #1250

References:

• PRD: Start/Pause/Resume the Task Workspace
• RFC: Tasks: Start/Pause/Resume Lifecycle: Notifications