feat: 新增代理分配套餐上架状态（shelf_status）功能

- 新增数据库迁移：为 shop_package_allocation 表添加 shelf_status 字段
- 更新模型/DTO：ShopPackageAllocation 增加 ShelfStatus 字段及相关枚举
- 更新套餐分配 Service：支持上架/下架状态管理逻辑
- 更新套餐 Store/Service：根据 shelf_status 过滤可售套餐
- 更新购买验证 Service：引入上架状态校验逻辑
- 归档 OpenSpec 变更：2026-03-02-agent-allocation-shelf-status
- 同步更新主规范文档：allocation-shelf-status、package-management、purchase-validation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/bootstrap/services.go

@@ -82,7 +82,7 @@ type services struct {
 }
 
 func initServices(s *stores, deps *Dependencies) *services {
-	purchaseValidation := purchaseValidationSvc.New(deps.DB, s.IotCard, s.Device, s.Package)
+	purchaseValidation := purchaseValidationSvc.New(deps.DB, s.IotCard, s.Device, s.Package, s.ShopPackageAllocation)
 	accountAudit := accountAuditSvc.NewService(s.AccountOperationLog)
 	account := accountSvc.New(s.Account, s.Role, s.AccountRole, s.ShopRole, s.Shop, s.Enterprise, accountAudit)