Add email notification preference for task completion

- Add EmailTaskCompleted field to NotificationPreference model
- Update notification repository to include email preference in queries
- Check email preference before sending task completion emails
- Add email preference toggle to admin panel notification-prefs page
- Update API types for email preference support

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/services/task_service.go

@@ -570,20 +570,25 @@ func (s *TaskService) sendTaskCompletedNotification(task *models.Task, completio
 		}
 
 		// Send email notification (to everyone INCLUDING the person who completed it)
-		if s.emailService != nil && user.Email != "" {
-			go func(u models.User) {
-				if err := s.emailService.SendTaskCompletedEmail(
-					u.Email,
-					u.GetFullName(),
-					task.Title,
-					completedByName,
-					residenceName,
-				); err != nil {
-					log.Error().Err(err).Str("email", u.Email).Uint("task_id", task.ID).Msg("Failed to send task completion email")
-				} else {
-					log.Info().Str("email", u.Email).Uint("task_id", task.ID).Msg("Task completion email sent")
-				}
-			}(user)
+		// Check user's email notification preferences first
+		if s.emailService != nil && user.Email != "" && s.notificationService != nil {
+			prefs, err := s.notificationService.GetPreferences(user.ID)
+			if err != nil || (prefs != nil && prefs.EmailTaskCompleted) {
+				// Send email if we couldn't get prefs (fail-open) or if email notifications are enabled
+				go func(u models.User) {
+					if err := s.emailService.SendTaskCompletedEmail(
+						u.Email,
+						u.GetFullName(),
+						task.Title,
+						completedByName,
+						residenceName,
+					); err != nil {
+						log.Error().Err(err).Str("email", u.Email).Uint("task_id", task.ID).Msg("Failed to send task completion email")
+					} else {
+						log.Info().Str("email", u.Email).Uint("task_id", task.ID).Msg("Task completion email sent")
+					}
+				}(user)
+			}
 		}
 	}
 }