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>

docker-compose.yml

@@ -0,0 +1,46 @@
+services:
+
+  db:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_DB: qa_test
+      POSTGRES_USER: qa_user
+      POSTGRES_PASSWORD: qa_password
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U qa_user -d qa_test"]
+      interval: 5s
+      timeout: 5s
+      retries: 10
+
+  backend:
+    build: ./backend
+    environment:
+      DATABASE_URL: postgresql+asyncpg://qa_user:qa_password@db:5432/qa_test
+    depends_on:
+      db:
+        condition: service_healthy
+    volumes:
+      - ./backend:/app
+
+  frontend:
+    build: ./frontend
+    volumes:
+      - ./frontend/src:/app/src
+      - ./frontend/index.html:/app/index.html
+    depends_on:
+      - backend
+
+  nginx:
+    image: nginx:alpine
+    ports:
+      - "80:80"
+    volumes:
+      - ./nginx/nginx.conf:/etc/nginx/conf.d/default.conf
+    depends_on:
+      - backend
+      - frontend
+
+volumes:
+  postgres_data: