* Add error handling for JSON encoding and HTTP server calls.
* Update passkey examples to improve readability and maintainability.
* Ensure consistent use of error handling across all examples.
- Implement DatabasePasskeyProvider for WebAuthn/FIDO2 authentication.
- Add methods for registration, authentication, and credential management.
- Create unit tests for passkey provider functionalities.
- Enhance DatabaseAuthenticator to support passkey authentication.