fix: cap Node.js heap to prevent OOM during wgc composition (#788)

## Summary
- Sets `NODE_OPTIONS=--max-old-space-size=64` in Dockerfile to cap Node.js heap when running `wgc router compose`
- Prevents container OOMKills in memory-constrained environments (e.g. acctest with 128Mi limit)
- The wgc Node.js process was using unbounded heap, which combined with the Go service easily exceeded container memory limits during rapid schema publishing

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Reviewed-on: #788

Dockerfile

@@ -30,6 +30,9 @@ ENV TZ Europe/Stockholm
 # Install wgc CLI globally for Cosmo Router composition
 RUN npm install -g wgc@latest
 
+# Cap Node.js heap for runtime wgc invocations to prevent OOM
+ENV NODE_OPTIONS="--max-old-space-size=64"
+
 # Copy timezone data and certificates
 COPY --from=build /usr/share/zoneinfo /usr/share/zoneinfo
 COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/