chore(backend): add Dockerfile for containerizing Node.js backend

Author: suresh-jakhar

backend/Dockerfile

@@ -0,0 +1,18 @@
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY tsconfig.json ./
+COPY src ./src
+COPY migrations ./migrations
+RUN npm run build
+
+FROM node:20-alpine AS runner
+WORKDIR /app
+ENV NODE_ENV=production
+COPY package*.json ./
+RUN npm ci --only=production
+COPY --from=builder /app/dist ./dist
+COPY --from=builder /app/migrations ./migrations
+EXPOSE 3001
+CMD ["node", "dist/index.js"]