Merge branch 'dev' into codex/update-project-documentation-and-version-number-0jh1p4

docs/CONTRIBUTING.en.md

@@ -94,6 +94,7 @@ Manually build WebUI to `static/admin/`:
 
 ```text
 ds2api/
+├── app/                    # Unified handler entry (shared by Vercel/local)
 ├── cmd/
 │   ├── ds2api/              # Local/container entrypoint
 │   └── ds2api-tests/        # End-to-end testsuite entrypoint

docs/CONTRIBUTING.md

@@ -94,6 +94,7 @@ docker-compose -f docker-compose.dev.yml up
 
 ```text
 ds2api/
+├── app/                    # 统一 Handler 入口（供 Vercel / 本地共用）
 ├── cmd/
 │   ├── ds2api/              # 本地/容器启动入口
 │   └── ds2api-tests/        # 端到端测试集入口