build: add Dockerfile and .dockerignore for containerized deployment

Dockerfile

@@ -0,0 +1,23 @@
+FROM node:20-alpine AS builder
+
+WORKDIR /app
+COPY package.json package-lock.json* ./
+RUN npm ci
+
+COPY . .
+RUN npm run build
+
+FROM node:20-alpine AS runner
+WORKDIR /app
+
+ENV NODE_ENV=production
+ENV PROXY_PORT=11437
+ENV PROXY_HOST=0.0.0.0
+
+COPY --from=builder /app/package.json ./
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/dist ./dist
+
+EXPOSE 11437
+
+CMD ["node", "dist/index.js"]