MasterKeyManager.loadKeytar() now bails out early when
FUSION_MASTER_KEY_DISABLE_KEYCHAIN=1, and the core vitest setup sets that
flag for every worker. Eight tests across master-key/secrets-store/
secrets-sync-passphrase were timing out at exactly the 15s testTimeout
because they constructed MasterKeyManager without injecting a fake
KeytarLike, which made loadKeytar() reach the real OS keychain.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
