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

tests/test_jobs_integration.py

@@ -0,0 +1,55 @@
+"""集成测试：GET /jobs/:id 走真实 DB（无 DB 时跳过）。
+
+get_sessionmaker 缓存的 async engine 绑定首个事件循环；pytest-asyncio 每个
+测试用新循环，故每个 DB 测试清缓存以在当前循环上重建 engine，并在结束 dispose。
+"""
+
+from __future__ import annotations
+
+from collections.abc import AsyncIterator
+
+import httpx
+import pytest
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+from ww_db import get_sessionmaker
+from ww_db.models import Job
+
+
+@pytest.fixture
+async def sm() -> AsyncIterator[async_sessionmaker[AsyncSession]]:
+    get_sessionmaker.cache_clear()
+    maker = get_sessionmaker()
+    try:
+        async with maker() as probe:
+            await probe.execute(text("select 1"))
+    except Exception:
+        pytest.skip("postgres not reachable")
+    yield maker
+    await maker.kw["bind"].dispose()
+    get_sessionmaker.cache_clear()
+
+
+async def test_get_job_returns_row(
+    client: httpx.AsyncClient, sm: async_sessionmaker[AsyncSession]
+) -> None:
+    async with sm() as s:
+        job = Job(kind="style_learn", status="running", progress=42)
+        s.add(job)
+        await s.commit()
+        job_id = job.id
+    resp = await client.get(f"/jobs/{job_id}")
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["kind"] == "style_learn"
+    assert body["progress"] == 42
+
+
+async def test_get_missing_job_returns_envelope(
+    client: httpx.AsyncClient, sm: async_sessionmaker[AsyncSession]
+) -> None:
+    resp = await client.get("/jobs/00000000-0000-0000-0000-000000000000")
+    assert resp.status_code == 404
+    err = resp.json()["error"]
+    assert err["code"] == "NOT_FOUND"
+    assert err["request_id"]