- Bump CURRENT_KEY_VERSION from 1 to 2 (v1 reserved for TS PBKDF2 legacy per ADR-020)
- Add derivation::encryption_path_for_version(version) -> m/74'/2'/0'/{version-2}', returns InvalidPath for version < 2
- Add VaultServiceHandle::derive_encryption_key_for_version(version), cached by path, returns InvalidPath for version < 2
- encrypt/decrypt now derive at encryption_path_for_version(key_version) instead of fixed PATHS::ENCRYPTION
- Add VaultServiceHandle::rotate(encrypted, to_version): decrypt old, re-encrypt new
- Update existing tests to use v2; add round-trip, rotation, partial-rotation, and invalid-version tests
Task: vault/key-versioning-rotation
Rename the crate from alknet-secret to alknet-vault to better reflect its
purpose as a local key vault (seed management, key derivation, encryption)
rather than a network service.
Symbol renames:
- SecretService → VaultService
- SecretServiceHandle → VaultServiceHandle
- SecretServiceActor → VaultServiceActor
- SecretServiceError → VaultServiceError
- SecretProtocol → VaultProtocol
- SecretMessage → VaultMessage
- ServiceLocked → VaultLocked
- alknet_secret → alknet_vault (crate name)
Update ADR-008 with vault access pattern: the vault is a capability source,
not a service endpoint. The CLI injects derived/decrypted material into
operation contexts — handlers never hold vault references.
