chore(docker): move Dockerfile and docker-compose.yml from wwjcloud-nest to root docker/

docker/Dockerfile

@@ -0,0 +1,44 @@
+# ========================================
+# NestJS Backend Dockerfile
+# ========================================
+FROM node:20-alpine AS builder
+
+WORKDIR /app
+
+# 复制package文件
+COPY package*.json ./
+
+# 安装所有依赖（包括 devDependencies，用于构建）
+RUN npm ci && npm cache clean --force
+
+# 复制源码
+COPY . .
+
+# 构建应用
+RUN npm run build
+
+# 删除 devDependencies，只保留生产依赖
+RUN npm prune --production
+
+# ========================================
+# Production Stage
+# ========================================
+FROM node:20-alpine
+
+WORKDIR /app
+
+# 复制依赖和构建产物
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/dist ./dist
+COPY --from=builder /app/package*.json ./
+
+# 暴露端口
+EXPOSE 3000
+
+# 健康检查
+HEALTHCHECK --interval=30s --timeout=3s --start-period=40s \
+  CMD node -e "require('http').get('http://localhost:3000/health', (r) => {process.exit(r.statusCode === 200 ? 0 : 1)})"
+
+# 启动应用
+CMD ["node", "dist/main"]
+