Fix healthcheck to respect runtime PORT

Co-authored-by: multica-agent <github@multica.ai>

Dockerfile

@@ -63,8 +63,10 @@ COPY --from=build /app/packages/game-engine packages/game-engine
 
 EXPOSE 3000
 
+# Coolify (and other hosts) override PORT at runtime; probe that port, not a
+# hardcoded one.
 HEALTHCHECK --interval=30s --timeout=5s --start-period=30s --retries=3 \
-  CMD node -e "fetch('http://127.0.0.1:3000/').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"
+  CMD node -e "fetch('http://127.0.0.1:' + (process.env.PORT || 3000) + '/').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"
 
 # The Nuxt web server reads its config through Nuxt runtimeConfig, which is
 # baked at build time and overridden at runtime only by NUXT_-prefixed env