fix: use node for Docker health check instead of curl

- Replace curl with node http.get in Docker CI workflow
- curl not available in node:20-slim based containers

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/docker.yml

@@ -24,7 +24,7 @@ jobs:
 
       - name: Verify backend health
         run: |
-          docker compose -f devops/docker-compose.yml exec -T backend curl -f http://localhost:5000/health || exit 1
+          docker compose -f devops/docker-compose.yml exec -T backend node -e "const h=require('http');h.get('http://localhost:5000/health',(r)=>{let d='';r.on('data',c=>d+=c);r.on('end',()=>{console.log(d);process.exit(r.statusCode===200?0:1)})}).on('error',e=>{console.error(e);process.exit(1)})"
 
       - name: Cleanup
         if: always()