- Replace hub/spoke terminology with head/worker throughout all research docs
- Add irpc service layer architecture (AuthProtocol, SecretProtocol,
ConfigProtocol, StorageProtocol)
- Add BIP39/SLIP-0010 HD key derivation for secrets management
- Add event boundary discipline (domain events vs integration events)
- Add application services layer (Docker, Node, Wallet, Proxy, Compute)
- New docs/research/services.md defining irpc service protocols
- Update core.md with service layer section and head/worker model
- Update configuration.md to delegate auth to AuthService (irpc)
- Update storage.md with secrets/key derivation and event boundaries
- Update flow.md with event boundary decision and cross-references
