- Replace hardcoded "ait-devnet" defaults with settings.chain_id throughout codebase
- Add get_chain_id() helper function in RPC router
- Update mempool methods to use settings.chain_id when chain_id is None
- Update blockchain node main to use settings.chain_id for gossip handlers
- Update RPC endpoints to accept None and default to settings.chain_id
- Update token supply endpoint to handle mainnet vs devnet (