Add Dockerfile for application setup

Dockerfile

@@ -0,0 +1,19 @@
+FROM node:18-alpine
+
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install dependencies
+RUN npm ci --only=production
+
+# Copy application code
+COPY . .
+
+# Build if needed
+RUN npm run build --if-present
+
+EXPOSE 3000
+
+CMD ["npm", "start"]