## Why
The user-verification API previously returned an unsupported provider on macOS. Enable native verification using biometric-protected credentials.
## What changed
- Implement credential status, creation, reuse, deletion, and challenge signing with P-256 Secure Enclave keys in the Data Protection Keychain.
- Require biometric authentication through the key's access-control policy and use a fresh `LAContext` for each signature.
- Report Touch ID hardware support independently of enrollment and current readiness, and map native failures to structured verification errors.
- Serialize credential operations across processes with cancellable file-lock waits. Invalidate pending authentication on cancellation and wait for the signer to exit before releasing the lock.
## Testing
Add unit tests for lock contention and cancellation, authentication teardown and late-result rejection, native error classification, and validation of Secure Enclave key attributes.
GitOrigin-RevId: 93268962cd824b2befc1a0c54b99dcb77a0f1044
e7637306bc