feat: Sprint 1 — infrastructure + test creation

Backend:
- FastAPI + SQLAlchemy 2.0 async + Alembic
- Models: Test, Question, Answer
- API: GET /api/tests, GET /api/tests/{id}, POST /api/tests
- Pydantic validation: min 7 questions, min 3 answers, ≥1 correct

Frontend:
- React 18 + TypeScript + Vite + Ant Design + TanStack Query
- Pages: TestList, TestCreate (nested Form.List), TestDetail

Infrastructure:
- Docker Compose: db (postgres:16), backend, frontend, nginx
- Nginx: /api/ → FastAPI, / → Vite dev server with HMR
- Alembic migration 001_init: tests, questions, answers tables
- entrypoint.sh: wait for db, migrate, start uvicorn

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/main.py

@@ -0,0 +1,20 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api import tests
+
+app = FastAPI(title="QA Test App API", version="0.1.0")
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(tests.router)
+
+
+@app.get("/api/health")
+async def health():
+    return {"status": "ok"}