The key rode the wholesale settings→localStorage save, sitting at rest
readable by any same-origin script, while the AES-256-GCM key-vault built
for exactly this sat bypassed. Now: the key lives in a memory-only store
ref, persists only into the encrypted vault when a passphrase session is
active (migrating into the vault on unlock), and a one-time migration lifts
any existing plaintext key out of localStorage and re-saves the scrubbed
settings object immediately. Settings UI reports honestly how the key is
held. Typecheck clean; test suite unchanged (348 pass, 3 pre-existing fails).
Co-Authored-By: Claude <noreply@anthropic.com>
