fix(docker): run under tini to reap zombie processes (#137)

Author: vignesh07

Dockerfile

@@ -46,6 +46,7 @@ ENV NODE_ENV=production
 RUN apt-get update \
   && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     ca-certificates \
+    tini \
   && rm -rf /var/lib/apt/lists/*
 
 # `openclaw update` expects pnpm. Provide it in the runtime image.
@@ -71,4 +72,7 @@ COPY src ./src
 # Railway injects PORT at runtime and routes traffic to that port.
 # If we force a different port, deployments can come up but the domain will route elsewhere.
 EXPOSE 3000
+
+# Ensure PID 1 reaps zombies and forwards signals.
+ENTRYPOINT ["tini", "--"]
 CMD ["node", "src/server.js"]