authenticatePresence
suspend fun authenticatePresence(activity: FragmentActivity, title: String = "Confirm it's you", subtitle: String? = null)
Presence-only authentication — shows the system biometric / device-credential prompt purely to confirm "it's you", with NO BiometricPrompt.CryptoObject and no crypto operation. For gating recoverable, non-secret actions (e.g. sign-out) where a TEE-bound CryptoObject would be overkill and would couple the action to the master key existing.
Returns normally on success; throws the same exception types as authenticateForEncrypt on cancel / lockout / failure so callers can treat cancellation as "abort the action, change nothing".