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）

.opencode/skills/openspec-continue-change/SKILL.md

@@ -102,7 +102,35 @@ Common artifact patterns:
   - The Capabilities section is critical - each capability listed will need a spec file.
 - **specs/<capability>/spec.md**: Create one spec per capability listed in the proposal's Capabilities section (use the capability name, not the change name).
 - **design.md**: Document technical decisions, architecture, and implementation approach.
-- **tasks.md**: Break down implementation into checkboxed tasks.
+- **tasks.md**: Break down implementation into checkboxed tasks, following TDD workflow structure:
+
+  **TDD Tasks Structure (MUST follow)**:
+  ```markdown
+  ## 0. 测试准备（实现前执行）
+  - [ ] 0.1 生成验收测试和流程测试（/opsx:gen-tests）
+  - [ ] 0.2 运行测试确认全部 FAIL（证明测试有效）
+
+  ## 1. 基础设施（数据库 + Model）
+  - [ ] 1.x 创建迁移、Model、DTO
+  - [ ] 1.y 验证：编译通过
+
+  ## 2. 功能单元 A（完整垂直切片）
+  - [ ] 2.1 Store 层
+  - [ ] 2.2 Service 层
+  - [ ] 2.3 Handler 层 + 路由
+  - [ ] 2.4 **验证：功能 A 相关验收测试 PASS**
+
+  ## N. 最终验证
+  - [ ] N.1 全部验收测试 PASS
+  - [ ] N.2 全部流程测试 PASS
+  - [ ] N.3 完整测试套件无回归
+  ```
+
+  **Key principles**:
+  - Task group 0 MUST be test preparation (generate tests + confirm all FAIL)
+  - Organize by functional units, NOT by technical layers (Store/Service/Handler)
+  - Each functional unit MUST end with "verify related tests PASS"
+  - Final validation MUST include all acceptance + flow tests passing
 
 For other schemas, follow the `instruction` field from the CLI output.