refactor(dockerfile): Update Node.js version and simplify Docker build process

- Changed base image from node:22-alpine to node:18-alpine
- Simplified Dockerfile by removing redundant comments
- Streamlined dependency installation and build steps
- Maintained pnpm as package manager

Dockerfile

@@ -1,26 +1,13 @@
-
-1. 首先创建 `Dockerfile`：
-
-```dockerfile
-FROM node:22-alpine
+FROM node:18-alpine
 
 WORKDIR /app
 
-# 安装 pnpm
-RUN npm config set registry https://registry.npmmirror.com && \
-    npm install -g pnpm && \
-    pnpm config set registry https://registry.npmmirror.com
-
-# 复制项目文件
+COPY package.json pnpm-lock.yaml ./
 COPY . .
 
-# 安装依赖
-RUN pnpm install
-
-# 构建项目
-RUN pnpm run build
+RUN npm install -g pnpm && \
+    pnpm install
 
 EXPOSE 8001
 
 CMD ["pnpm", "start"]
-```