feat: 实现一次性佣金功能

- 新增佣金计算服务，支持一次性佣金和返佣计算
- 新增 ShopSeriesOneTimeCommissionTier 模型和存储层
- 新增两个数据库迁移：一次性佣金表和订单佣金字段
- 更新 Commission 模型，新增佣金来源和关联字段
- 更新 CommissionRecord 存储层，支持一次性佣金查询
- 更新 MyCommission 服务，集成一次性佣金计算逻辑
- 更新 ShopCommission 服务，支持一次性佣金统计
- 新增佣金计算异步任务处理器
- 更新 API 路由，新增一次性佣金相关端点
- 归档 OpenSpec 变更文档，同步规范到主规范库

internal/bootstrap/stores.go

@@ -31,6 +31,7 @@ type stores struct {
 	Package                           *postgres.PackageStore
 	ShopSeriesAllocation              *postgres.ShopSeriesAllocationStore
 	ShopSeriesCommissionTier          *postgres.ShopSeriesCommissionTierStore
+	ShopSeriesOneTimeCommissionTier   *postgres.ShopSeriesOneTimeCommissionTierStore
 	ShopSeriesAllocationConfig        *postgres.ShopSeriesAllocationConfigStore
 	ShopPackageAllocation             *postgres.ShopPackageAllocationStore
 	ShopPackageAllocationPriceHistory *postgres.ShopPackageAllocationPriceHistoryStore
@@ -67,6 +68,7 @@ func initStores(deps *Dependencies) *stores {
 		Package:                           postgres.NewPackageStore(deps.DB),
 		ShopSeriesAllocation:              postgres.NewShopSeriesAllocationStore(deps.DB),
 		ShopSeriesCommissionTier:          postgres.NewShopSeriesCommissionTierStore(deps.DB),
+		ShopSeriesOneTimeCommissionTier:   postgres.NewShopSeriesOneTimeCommissionTierStore(deps.DB),
 		ShopSeriesAllocationConfig:        postgres.NewShopSeriesAllocationConfigStore(deps.DB),
 		ShopPackageAllocation:             postgres.NewShopPackageAllocationStore(deps.DB),
 		ShopPackageAllocationPriceHistory: postgres.NewShopPackageAllocationPriceHistoryStore(deps.DB),