ci: add Dockerfile for deployment

Dockerfile

@@ -0,0 +1,22 @@
+FROM node:18-alpine AS builder
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm install
+
+COPY . .
+RUN npm run build
+
+FROM node:18-alpine
+
+WORKDIR /app
+
+COPY --from=builder /app/.next ./.next
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/package.json ./package.json
+COPY --from=builder /app/public ./public
+
+EXPOSE 3000
+
+CMD ["npm", "start"]