📝 docs(payment): update wechat refund integration testing section

- remove redundant architecture reference link
- update integration test framework to "Vitest + hono/testing"
- correct test folder location from "__tests__" to "tests"

docs/stories/011.003.wechat-payment-refund-integration.story.md

@@ -106,10 +106,10 @@ Draft
 - **退款记录服务**: `packages/orders-module-mt/src/services/user-refunds.mt.service.ts:1-50` (创建退款记录)
 
 ### Testing Requirements
-**测试框架** [Source: architecture/coding-standards.md]
+**测试框架**
 - **单元测试**: Vitest
-- **集成测试**: hono/testing
-- **测试位置**: `__tests__` 文件夹与源码并列
+- **集成测试**: Vitest + hono/testing
+- **测试位置**: `tests` 文件夹与源码并列
 - **覆盖率目标**: 核心业务逻辑 > 80%
 
 **退款测试场景**