feat: 完成 opsx-licence 许可证管理平台全栈实现

基于 opsx-web-lite 框架（Go+Gin+Vue3+Element Plus）构建许可证管理服务器，
业务域参考 Licence 服务器 Web 版。

【后端 - 4层架构】
- 认证：单 Admin 表 + JWT（HS256）
- 核心授权域：Product / Customer / License / Activation
  · License 生成/验证/激活/机器绑定/心跳/续期/吊销
  · 客户端契约接口：/api/v1/license/{verify,activate,deactivate,heartbeat}
- 定价订单：Plan / Order / 支付网关配置
- 防重复购买：CustomerEntitlement + 幂等支付 webhook + 手动发放
- 分析审计：Dashboard 统计 / Analytics / AuditLog / Setting 管理

【前端】
- Dashboard（ECharts 图表）、产品、客户、License、计划、订单、权益、日志、设置
- 9 个完整 CRUD 业务页面 + 登录/布局

【部署】
- SQLite + 单二进制（//go:embed 嵌入前端）
- 开发：./run.sh start（前端5181/后端9001）
- 生产：./run.sh build && ./run.sh binary start
- 默认账号：admin/admin

Author: Logan.Li

backend/internal/service/license/client_service.go

@@ -0,0 +1,158 @@
+package license
+
+import (
+	"backend/internal/dto"
+	"backend/internal/model"
+	"backend/utils"
+	"errors"
+	"time"
+)
+
+// Verify 客户端 License 验证 // Logan.Li
+func (s *LicenseService) Verify(req dto.LicenseVerifyRequest) (*dto.LicenseVerifyResponse, error) {
+	var lic model.License
+	if err := s.db.Preload("Product").Where("license_key = ?", req.LicenseKey).First(&lic).Error; err != nil {
+		return &dto.LicenseVerifyResponse{Valid: false, Message: "无效的 License"}, nil
+	}
+
+	// 校验产品归属 // Logan.Li
+	if req.ProductID > 0 && lic.ProductID != req.ProductID {
+		return &dto.LicenseVerifyResponse{Valid: false, Message: "License 与产品不匹配"}, nil
+	}
+
+	// 状态检查 // Logan.Li
+	switch lic.Status {
+	case model.LicenseStatusRevoked:
+		return &dto.LicenseVerifyResponse{Valid: false, Message: "License 已被吊销"}, nil
+	case model.LicenseStatusSuspended:
+		return &dto.LicenseVerifyResponse{Valid: false, Message: "License 已被暂停"}, nil
+	case model.LicenseStatusExpired:
+		return &dto.LicenseVerifyResponse{Valid: false, Message: "License 已过期"}, nil
+	}
+
+	// 过期检查（惰性更新状态） // Logan.Li
+	if utils.IsLicenseExpired(lic.EndDate) {
+		lic.Status = model.LicenseStatusExpired
+		s.db.Save(&lic)
+		return &dto.LicenseVerifyResponse{Valid: false, Message: "License 已过期"}, nil
+	}
+
+	return &dto.LicenseVerifyResponse{
+		Valid:       true,
+		LicenseKey:  lic.LicenseKey,
+		ProductID:   lic.ProductID,
+		ProductName: lic.Product.Name,
+		ProductCode: lic.Product.Code,
+		Features:    utils.ParseFeatures(lic.Product.Features),
+		Status:      lic.Status,
+		ExpiresAt:   lic.EndDate.Format("2006-01-02 15:04:05"),
+		DaysLeft:    utils.CalculateDaysLeft(lic.EndDate),
+		MaxDevices:  lic.MaxActivations,
+		Message:     "验证成功",
+	}, nil
+}
+
+// Activate 客户端激活 License（机器绑定） // Logan.Li
+func (s *LicenseService) Activate(req dto.LicenseActivateRequest, clientIP string) (map[string]interface{}, error) {
+	var lic model.License
+	if err := s.db.Where("license_key = ?", req.LicenseKey).First(&lic).Error; err != nil {
+		return nil, errors.New("无效的 License")
+	}
+
+	if lic.Status == model.LicenseStatusRevoked {
+		return nil, errors.New("License 已被吊销")
+	}
+	if lic.Status == model.LicenseStatusExpired || utils.IsLicenseExpired(lic.EndDate) {
+		return nil, errors.New("License 已过期")
+	}
+
+	// 同设备重复激活视为重新激活，不消耗额度 // Logan.Li
+	var existing model.Activation
+	if err := s.db.Where("license_id = ? AND device_id = ?", lic.ID, req.DeviceID).First(&existing).Error; err == nil {
+		existing.LastSeenAt = time.Now()
+		existing.IsOnline = true
+		existing.DeviceName = req.DeviceName
+		existing.DeviceInfo = req.DeviceInfo
+		existing.IP = clientIP
+		s.db.Save(&existing)
+		return map[string]interface{}{
+			"expires_at": lic.EndDate.Format("2006-01-02 15:04:05"),
+			"days_left":  utils.CalculateDaysLeft(lic.EndDate),
+		}, nil
+	}
+
+	// 检查激活额度 // Logan.Li
+	if lic.CurrentActivations >= lic.MaxActivations {
+		return nil, errors.New("已达到最大激活数量限制")
+	}
+
+	// 创建激活记录 // Logan.Li
+	activation := model.Activation{
+		LicenseID:   lic.ID,
+		DeviceID:    req.DeviceID,
+		DeviceName:  req.DeviceName,
+		DeviceInfo:  req.DeviceInfo,
+		IP:          clientIP,
+		Status:      "active",
+		IsOnline:    true,
+		ActivatedAt: time.Now(),
+		LastSeenAt:  time.Now(),
+	}
+	if err := s.db.Create(&activation).Error; err != nil {
+		return nil, errors.New("激活失败")
+	}
+
+	lic.CurrentActivations++
+	if lic.Status == model.LicenseStatusInactive {
+		lic.Status = model.LicenseStatusActive
+	}
+	s.db.Save(&lic)
+
+	return map[string]interface{}{
+		"expires_at": lic.EndDate.Format("2006-01-02 15:04:05"),
+		"days_left":  utils.CalculateDaysLeft(lic.EndDate),
+	}, nil
+}
+
+// Deactivate 客户端停用 // Logan.Li
+func (s *LicenseService) Deactivate(req dto.LicenseDeactivateRequest) error {
+	var lic model.License
+	if err := s.db.Where("license_key = ?", req.LicenseKey).First(&lic).Error; err != nil {
+		return errors.New("无效的 License")
+	}
+
+	result := s.db.Model(&model.Activation{}).
+		Where("license_id = ? AND device_id = ?", lic.ID, req.DeviceID).
+		Update("status", "inactive")
+
+	if result.RowsAffected > 0 && lic.CurrentActivations > 0 {
+		lic.CurrentActivations--
+		s.db.Save(&lic)
+	}
+	return nil
+}
+
+// Heartbeat 客户端心跳 // Logan.Li
+func (s *LicenseService) Heartbeat(req dto.LicenseHeartbeatRequest) (map[string]interface{}, error) {
+	var lic model.License
+	if err := s.db.Where("license_key = ?", req.LicenseKey).First(&lic).Error; err != nil {
+		return nil, errors.New("无效的 License")
+	}
+
+	if lic.Status == model.LicenseStatusRevoked {
+		return nil, errors.New("License 已被吊销")
+	}
+	if lic.Status == model.LicenseStatusExpired || utils.IsLicenseExpired(lic.EndDate) {
+		return nil, errors.New("License 已过期")
+	}
+
+	// 更新心跳时间与在线状态 // Logan.Li
+	s.db.Model(&model.Activation{}).
+		Where("license_id = ? AND device_id = ?", lic.ID, req.DeviceID).
+		Updates(map[string]interface{}{"last_seen_at": time.Now(), "is_online": true})
+
+	return map[string]interface{}{
+		"expires_at": lic.EndDate.Format("2006-01-02 15:04:05"),
+		"days_left":  utils.CalculateDaysLeft(lic.EndDate),
+	}, nil
+}