The stub previously panicked on all methods including NewKeychainUnlocker,
which is called from vault code when processing keychain-type unlocker
metadata. This caused crashes on Linux/Windows when a vault synced from
macOS contained keychain unlockers.
Now returns proper error values, allowing graceful degradation and
cross-platform vault portability.
The decrypted data from io.ReadAll was copied into a memguard
LockedBuffer but the original byte slice was never zeroed, leaving
plaintext in swappable, dumpable heap memory.
clawbot