style: fix gofmt struct tag alignment

backend/internal/handler/admin/redeem_handler.go

@@ -36,8 +36,8 @@ type GenerateRedeemCodesRequest struct {
 	Count        int     `json:"count" binding:"required,min=1,max=100"`
 	Type         string  `json:"type" binding:"required,oneof=balance concurrency subscription invitation"`
 	Value        float64 `json:"value"`
-	GroupID      *int64  `json:"group_id"`        // 订阅类型必填
-	ValidityDays int     `json:"validity_days"`   // 订阅类型使用，正数增加/负数退款扣减
+	GroupID      *int64  `json:"group_id"`      // 订阅类型必填
+	ValidityDays int     `json:"validity_days"` // 订阅类型使用，正数增加/负数退款扣减
 }
 
 // CreateAndRedeemCodeRequest represents creating a fixed code and redeeming it for a target user.
@@ -47,8 +47,8 @@ type CreateAndRedeemCodeRequest struct {
 	Type         string  `json:"type" binding:"omitempty,oneof=balance concurrency subscription invitation"` // 不传时默认 balance（向后兼容）
 	Value        float64 `json:"value" binding:"required"`
 	UserID       int64   `json:"user_id" binding:"required,gt=0"`
-	GroupID      *int64  `json:"group_id"`        // subscription 类型必填
-	ValidityDays int     `json:"validity_days"`   // subscription 类型：正数增加，负数退款扣减
+	GroupID      *int64  `json:"group_id"`      // subscription 类型必填
+	ValidityDays int     `json:"validity_days"` // subscription 类型：正数增加，负数退款扣减
 	Notes        string  `json:"notes"`
 }