feat: 完成 Docker Compose 配置 (TASK-005)

- 创建 docker-compose.yml 定义三服务架构
- 创建 backend/Dockerfile (Python 3.12)
- 创建 frontend/Dockerfile (Node 20)
- 创建 .dockerignore 文件
- 验证配置语法正确
- 配置 healthcheck 和服务依赖

服务：
- postgres: PostgreSQL 15
- backend: FastAPI + uvicorn
- frontend: Next.js dev server

任务状态：TASK-005 已完成
下一步：TASK-006 后端核心配置

Assisted-by: Kiro AI <kiro@cursor.com>

docker-compose.yml

@@ -1,7 +1,8 @@
+version: '3.8'
+
 services:
   postgres:
     image: postgres:15-alpine
-    container_name: s2f-postgres
     environment:
       POSTGRES_DB: s2f_db
       POSTGRES_USER: s2f_user
@@ -15,6 +16,36 @@ services:
       interval: 10s
       timeout: 5s
       retries: 5
+  
+  backend:
+    build: ./backend
+    environment:
+      DATABASE_URL: postgresql+asyncpg://s2f_user:s2f_password@postgres:5432/s2f_db
+      ALLOWED_ORIGINS: '["http://localhost:3000"]'
+      DEBUG: "true"
+    ports:
+      - "8000:8000"
+    volumes:
+      - ./backend:/app
+      - ./backend/uploads:/app/uploads
+    depends_on:
+      postgres:
+        condition: service_healthy
+    command: uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload
+  
+  frontend:
+    build: ./frontend
+    environment:
+      NEXT_PUBLIC_API_URL: http://localhost:8000
+      NEXT_PUBLIC_APP_NAME: "财务 AI 助手（薪财通 AI）"
+    ports:
+      - "3000:3000"
+    volumes:
+      - ./frontend:/app
+      - /app/node_modules
+      - /app/.next
+    depends_on:
+      - backend
 
 volumes:
   postgres_data: