fix: use multi-stage Docker build to prevent OOM during tsc

The @vechain/vebetterdao-contracts typechain types exhaust the default
heap when compiling inside Alpine. Split into a builder stage with a 4GB
heap limit and a slim runtime stage with production-only deps.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Agilulfo1820

Dockerfile

@@ -1,9 +1,15 @@
-FROM node:20-alpine
+FROM node:20-alpine AS builder
 WORKDIR /app
 COPY package.json ./
-RUN npm install --production
+RUN npm install
 COPY tsconfig.json ./
 COPY src ./src
-RUN npx tsc
+RUN NODE_OPTIONS=--max-old-space-size=4096 npx tsc
+
+FROM node:20-alpine
+WORKDIR /app
+COPY package.json ./
+RUN npm install --production
+COPY --from=builder /app/dist ./dist
 ENV RELAYER_NETWORK=testnet-staging
 CMD ["node", "dist/index.js"]