Biometric lock: opt-in Face ID/Touch ID/fingerprint app lock with toggle
in ProfileScreen. Locks on background, requires auth on foreground return.
Platform implementations: BiometricPrompt (Android), LAContext (iOS).
Rate limit: 429 responses parsed with Retry-After header, user-friendly
error messages in all 10 locales, retry plugin respects 429.
ErrorMessageParser updated for both iOS Swift and KMM.
0d80df07f6