Add aftersales stats to dashboard and service-layer tests

- CompanyStatsOverviewDTO and GetStats() now include aftersales counts
  (total, pending confirmation, closed, rejected) and a recentAftersales list
- aftersales_service_test.go covers YYMMNN sequence, owner-only submit,
  state machine, phone last-4 check, reject increment, force-close
- users_service_test.go covers duplicate username, self-demotion guard,
  last-admin guard, password reset, assignable filter

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/companies_service.go

@@ -317,6 +317,11 @@ func (s *CompaniesService) GetStats() (map[string]any, error) {
 		return nil, errors.New("查询员工序列号统计失败")
 	}
 
+	var aftersales []models.AftersalesOrder
+	if err := database.DB.Preload("Technician").Order("created_at DESC").Find(&aftersales).Error; err != nil {
+		return nil, errors.New("查询售后工单统计失败")
+	}
+
 	companyCount := len(companies)
 	serialCount := len(serials)
 	employeeSerialCount := len(employeeSerials)
@@ -392,6 +397,41 @@ func (s *CompaniesService) GetStats() (map[string]any, error) {
 		recentSerials = recentSerials[:10]
 	}
 
+	aftersalesTotal := len(aftersales)
+	aftersalesPending := 0
+	aftersalesClosed := 0
+	aftersalesRejected := 0
+	for _, o := range aftersales {
+		switch o.WorkOrderStatus {
+		case "pending_confirmation":
+			aftersalesPending++
+		case "closed":
+			aftersalesClosed++
+		case "rejected":
+			aftersalesRejected++
+		}
+	}
+
+	recentAftersales := make([]map[string]any, 0)
+	for i, order := range aftersales {
+		if i >= 10 {
+			break
+		}
+		technicianName := ""
+		if order.Technician != nil {
+			technicianName = order.Technician.Name
+		}
+		recentAftersales = append(recentAftersales, map[string]any{
+			"serialNumber":        order.SerialNumber,
+			"companyName":         order.CompanyName,
+			"serviceType":         order.ServiceType,
+			"workOrderStatus":     order.WorkOrderStatus,
+			"authorizationStatus": order.AuthorizationStatus,
+			"technicianName":      technicianName,
+			"createdAt":           order.CreatedAt,
+		})
+	}
+
 	return map[string]any{
 		"overview": map[string]any{
 			"totalCompanies":       companyCount,
@@ -399,10 +439,15 @@ func (s *CompaniesService) GetStats() (map[string]any, error) {
 			"totalEmployeeSerials": employeeSerialCount,
 			"activeSerials":        activeCount,
 			"inactiveSerials":      inactiveCount,
+			"totalAftersales":      aftersalesTotal,
+			"pendingConfirmation":  aftersalesPending,
+			"closedAftersales":     aftersalesClosed,
+			"rejectedAftersales":   aftersalesRejected,
 		},
-		"monthlyStats":    monthlyItems,
-		"recentCompanies": recentCompanies,
-		"recentSerials":   recentSerials,
+		"monthlyStats":     monthlyItems,
+		"recentCompanies":  recentCompanies,
+		"recentSerials":    recentSerials,
+		"recentAftersales": recentAftersales,
 	}, nil
 }
 
@@ -440,5 +485,18 @@ func (s *CompaniesService) GetStatsOverview() (*models.CompanyStatsOverviewDTO,
 
 	stats.RevokedEmployeeSerials = stats.TotalEmployeeSerials - stats.ActiveEmployeeSerials
 
+	if err := database.DB.Model(&models.AftersalesOrder{}).Count(&stats.TotalAftersales).Error; err != nil {
+		return nil, errors.New("统计售后工单总数失败")
+	}
+	if err := database.DB.Model(&models.AftersalesOrder{}).Where("work_order_status = ?", "pending_confirmation").Count(&stats.PendingConfirmation).Error; err != nil {
+		return nil, errors.New("统计待客户确认工单失败")
+	}
+	if err := database.DB.Model(&models.AftersalesOrder{}).Where("work_order_status = ?", "closed").Count(&stats.ClosedAftersales).Error; err != nil {
+		return nil, errors.New("统计已完成工单失败")
+	}
+	if err := database.DB.Model(&models.AftersalesOrder{}).Where("work_order_status = ?", "rejected").Count(&stats.RejectedAftersales).Error; err != nil {
+		return nil, errors.New("统计已退回工单失败")
+	}
+
 	return stats, nil
 }