build: remove pnpm install from Dockerfile

The pnpm install step is removed to optimize the Docker build process. The dependencies will be installed in a later stage when needed.

Dockerfile

@@ -12,7 +12,7 @@ WORKDIR /app
 COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
 
 # 安装 pnpm 和依赖（工作空间）
-RUN npm install -g pnpm && pnpm install
+RUN npm install -g pnpm
 
 # 复制源代码
 COPY . .