feat: 添加 Docker 支持与项目文档

- 添加 Dockerfile, docker-compose.yml, .dockerignore, nginx 配置
- 添加后端 API 设计文档、平台架构需求文档、系统开发计划
- 添加 PostgreSQL schema 设计
- 更新 README.md 和 design-qa.md

Dockerfile

@@ -0,0 +1,19 @@
+# syntax=docker/dockerfile:1
+
+FROM node:20-alpine AS build
+WORKDIR /app/frontend
+
+COPY frontend/package*.json ./
+RUN npm ci
+
+COPY frontend/ ./
+RUN npm run build
+
+FROM nginx:1.27-alpine
+COPY docker/nginx.conf.template /etc/nginx/templates/default.conf.template
+COPY --from=build /app/frontend/dist /usr/share/nginx/html
+
+EXPOSE 80
+
+HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
+  CMD wget -qO- http://127.0.0.1/ >/dev/null || exit 1