feat: Phase 0 — monorepo 骨架 + 全表迁移 + FastAPI/Next 骨架 + CI

- uv(workspace) + pnpm monorepo；docker-compose(pg+api+web)
- SQLAlchemy 16 MVP 表 + Alembic 初版迁移(无漂移，users stub)
- FastAPI 骨架：统一错误信封(带 request_id) + structlog + /jobs/:id + OpenAPI
- Next.js 骨架：纸感主题 token + OpenAPI→TS 客户端代码生成(gen:api)
- CI(ruff/mypy/pytest + pg service + alembic 漂移校验)
- 四份设计规格(PRODUCT/UX/ARCHITECTURE/DEV_PLAN) + CLAUDE.md

apps/api/ww_api/middleware.py

@@ -0,0 +1,28 @@
+"""request_id 关联中间件（ARCH §9.3 / CLAUDE.md）。
+
+每请求生成/透传 request_id，绑入 structlog contextvars，并回写响应头，
+错误信封也带上同一 id，便于端到端 grep。
+"""
+
+from __future__ import annotations
+
+import uuid
+from collections.abc import Awaitable, Callable
+
+import structlog
+from starlette.requests import Request
+from starlette.responses import Response
+
+REQUEST_ID_HEADER = "x-request-id"
+
+
+async def request_id_middleware(
+    request: Request, call_next: Callable[[Request], Awaitable[Response]]
+) -> Response:
+    request_id = request.headers.get(REQUEST_ID_HEADER) or uuid.uuid4().hex
+    structlog.contextvars.clear_contextvars()
+    structlog.contextvars.bind_contextvars(request_id=request_id)
+    request.state.request_id = request_id
+    response = await call_next(request)
+    response.headers[REQUEST_ID_HEADER] = request_id
+    return response