Add Dockerfile for Node.js backend setup

web/server/Dockerfile

@@ -0,0 +1,17 @@
+# Node.js backend
+FROM node:18-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+
+RUN npm install --omit=dev
+
+COPY . .
+
+EXPOSE 3001
+
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+  CMD node -e "require('http').get('http://localhost:3001/api/health', (r) => {process.exit(r.statusCode === 200 ? 0 : 1)})"
+
+CMD ["node", "server.js"]