- Add default_peer_rpc_url=http://127.0.0.1:8006 to blockchain-node .env.example and examples/env.example
- Extract set_env() helper function in setup.sh to handle env key-value updates (add if missing, update if exists)
- Ensure gossip_backend, gossip_broadcast_url, and default_peer_rpc_url are set in setup.sh node identity initialization
- Replace all sed -i commands with set_env() calls in workflow scripts
