refactor: 一次性佣金配置从套餐级别提升到系列级别

主要变更:
- 新增 tb_shop_series_allocation 表，存储系列级别的一次性佣金配置
- ShopPackageAllocation 移除 one_time_commission_amount 字段
- PackageSeries 新增 enable_one_time_commission 字段控制是否启用一次性佣金
- 新增 /api/admin/shop-series-allocations CRUD 接口
- 佣金计算逻辑改为从 ShopSeriesAllocation 获取一次性佣金金额
- 删除废弃的 ShopSeriesOneTimeCommissionTier 模型
- OpenAPI Tag '系列分配' 和 '单套餐分配' 合并为 '套餐分配'

迁移脚本:
- 000042: 重构佣金套餐模型
- 000043: 简化佣金分配
- 000044: 一次性佣金分配重构
- 000045: PackageSeries 添加 enable_one_time_commission 字段

测试:
- 新增验收测试 (shop_series_allocation, commission_calculation)
- 新增流程测试 (one_time_commission_chain)
- 删除过时的单元测试（已被验收测试覆盖）

internal/service/purchase_validation/service.go

@@ -11,11 +11,10 @@ import (
 )
 
 type Service struct {
-	db                    *gorm.DB
-	iotCardStore          *postgres.IotCardStore
-	deviceStore           *postgres.DeviceStore
-	packageStore          *postgres.PackageStore
-	seriesAllocationStore *postgres.ShopSeriesAllocationStore
+	db           *gorm.DB
+	iotCardStore *postgres.IotCardStore
+	deviceStore  *postgres.DeviceStore
+	packageStore *postgres.PackageStore
 }
 
 func New(
@@ -23,14 +22,12 @@ func New(
 	iotCardStore *postgres.IotCardStore,
 	deviceStore *postgres.DeviceStore,
 	packageStore *postgres.PackageStore,
-	seriesAllocationStore *postgres.ShopSeriesAllocationStore,
 ) *Service {
 	return &Service{
-		db:                    db,
-		iotCardStore:          iotCardStore,
-		deviceStore:           deviceStore,
-		packageStore:          packageStore,
-		seriesAllocationStore: seriesAllocationStore,
+		db:           db,
+		iotCardStore: iotCardStore,
+		deviceStore:  deviceStore,
+		packageStore: packageStore,
 	}
 }
 
@@ -39,7 +36,6 @@ type PurchaseValidationResult struct {
 	Device     *model.Device
 	Packages   []*model.Package
 	TotalPrice int64
-	Allocation *model.ShopSeriesAllocation
 }
 
 func (s *Service) ValidateCardPurchase(ctx context.Context, cardID uint, packageIDs []uint) (*PurchaseValidationResult, error) {