feat(subscribe): add traffic limit rules and user traffic stats

- Add subscribe traffic_limit schema and migration\n- Support traffic_limit in admin create/update and list/details\n- Apply traffic_limit when building server user list speed limits\n- Add public user traffic stats API

internal/logic/admin/group/createNodeGroupLogic.go

@@ -2,6 +2,7 @@ package group
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/perfect-panel/server/internal/model/group"
@@ -25,17 +26,51 @@ func NewCreateNodeGroupLogic(ctx context.Context, svcCtx *svc.ServiceContext) *C
 }
 
 func (l *CreateNodeGroupLogic) CreateNodeGroup(req *types.CreateNodeGroupRequest) error {
+	// 验证:系统中只能有一个过期节点组
+	if req.IsExpiredGroup != nil && *req.IsExpiredGroup {
+		var count int64
+		err := l.svcCtx.DB.Model(&group.NodeGroup{}).
+			Where("is_expired_group = ?", true).
+			Count(&count).Error
+		if err != nil {
+			logger.Errorf("failed to check expired group count: %v", err)
+			return err
+		}
+		if count > 0 {
+			return errors.New("system already has an expired node group, cannot create multiple")
+		}
+	}
+
 	// 创建节点组
 	nodeGroup := &group.NodeGroup{
-		Name:           req.Name,
-		Description:    req.Description,
-		Sort:           req.Sort,
-		ForCalculation: req.ForCalculation,
-		MinTrafficGB:   req.MinTrafficGB,
-		MaxTrafficGB:   req.MaxTrafficGB,
-		CreatedAt:      time.Now(),
-		UpdatedAt:      time.Now(),
+		Name:                req.Name,
+		Description:         req.Description,
+		Sort:                req.Sort,
+		ForCalculation:      req.ForCalculation,
+		IsExpiredGroup:      req.IsExpiredGroup,
+		MaxTrafficGBExpired: req.MaxTrafficGBExpired,
+		MinTrafficGB:        req.MinTrafficGB,
+		MaxTrafficGB:        req.MaxTrafficGB,
+		CreatedAt:           time.Now(),
+		UpdatedAt:           time.Now(),
 	}
+
+	// 设置过期节点组的默认值
+	if req.IsExpiredGroup != nil && *req.IsExpiredGroup {
+		// 过期节点组不参与分组计算
+		falseValue := false
+		nodeGroup.ForCalculation = &falseValue
+
+		if req.ExpiredDaysLimit != nil {
+			nodeGroup.ExpiredDaysLimit = *req.ExpiredDaysLimit
+		} else {
+			nodeGroup.ExpiredDaysLimit = 7 // 默认7天
+		}
+		if req.SpeedLimit != nil {
+			nodeGroup.SpeedLimit = *req.SpeedLimit
+		}
+	}
+
 	if err := l.svcCtx.DB.Create(nodeGroup).Error; err != nil {
 		logger.Errorf("failed to create node group: %v", err)
 		return err