Add quick-complete endpoint for iOS widget task completion

- Add lightweight POST /api/tasks/:id/quick-complete/ endpoint
- Creates task completion with minimal processing for widget use
- Returns only 200 OK on success (no response body)
- Updates task status and next_due_date based on frequency
- Sends completion notification asynchronously

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

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

internal/services/task_service.go

@@ -593,6 +593,65 @@ func (s *TaskService) CreateCompletion(req *requests.CreateTaskCompletionRequest
 	}, nil
 }
 
+// QuickComplete creates a minimal task completion (for widget use)
+// Returns only success/error, no response body
+func (s *TaskService) QuickComplete(taskID uint, userID uint) error {
+	// Get the task
+	task, err := s.taskRepo.FindByID(taskID)
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return ErrTaskNotFound
+		}
+		return err
+	}
+
+	// Check access
+	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
+	if err != nil {
+		return err
+	}
+	if !hasAccess {
+		return ErrTaskAccessDenied
+	}
+
+	completedAt := time.Now().UTC()
+
+	completion := &models.TaskCompletion{
+		TaskID:        taskID,
+		CompletedByID: userID,
+		CompletedAt:   completedAt,
+		Notes:         "Completed from widget",
+	}
+
+	if err := s.taskRepo.CreateCompletion(completion); err != nil {
+		return err
+	}
+
+	// Update next_due_date and status based on frequency
+	if task.Frequency == nil || task.Frequency.Days == nil || *task.Frequency.Days == 0 {
+		// One-time task - clear next_due_date and set status to "Completed" (ID=3)
+		task.NextDueDate = nil
+		completedStatusID := uint(3)
+		task.StatusID = &completedStatusID
+	} else {
+		// Recurring task - calculate next due date from completion date + frequency
+		nextDue := completedAt.AddDate(0, 0, *task.Frequency.Days)
+		task.NextDueDate = &nextDue
+
+		// Reset status to "Pending" (ID=1)
+		pendingStatusID := uint(1)
+		task.StatusID = &pendingStatusID
+	}
+	if err := s.taskRepo.Update(task); err != nil {
+		log.Error().Err(err).Uint("task_id", task.ID).Msg("Failed to update task after quick completion")
+	}
+
+	// Send notification (fire and forget)
+	go s.sendTaskCompletedNotification(task, completion)
+
+	return nil
+}
+
 // sendTaskCompletedNotification sends notifications when a task is completed
 func (s *TaskService) sendTaskCompletedNotification(task *models.Task, completion *models.TaskCompletion) {
 	// Get all users with access to this residence