feat: update backend Dockerfile for Node.js app

backend/Dockerfile

@@ -1,23 +1,13 @@
-# Use Node.js 22 LTS as base image
 FROM node:22-alpine
 
-# Set working directory
 WORKDIR /app
 
-# Copy package files
 COPY package*.json ./
+RUN npm ci --only=production
 
-# Install dependencies
-RUN npm ci
-
-# Copy source code
 COPY . .
-
-# Build the application
 RUN npm run build
 
-# Expose port 3001
 EXPOSE 3001
 
-# Run the application
+CMD ["node", "dist/index.js"]
-CMD ["npm", "start"]