Consider storing Passkey credentials in the device Secure Element

### Checks

- [x] I have read the Wiki, searched the open issues, and still think this is a new feature.

### Explain the problem clearly and succinctly:

Passkey credentials are currently not stored in the Secure Element and doing so would greatly increase the security of your credentials. Of course this depends on the security of your Secure Element.

### Describe the solution you'd like:

For passkey credentials to be stored in the Secure Element. https://developer.android.com/privacy-and-security/keystore. This can be optional as it not all devices have a Secure Element or a particularly strong one but for devices such as Google Pixels with their Titan M2 Secure Element, this would be a massive addition.

This would be similar to what Google Password Manager and this [app](https://codeberg.org/s1m/hw-fido2-provider) already do.

### Describe alternatives you've considered:

_No response_

### Additional context:

_No response_

Start with the Android Keystore documentation linked in the issue and trace how passkey credentials are currently stored. Determine how optional Secure Element storage could work on supported devices while retaining a fallback for others. Done means the security behavior is validated on supported and unsupported devices.

Written by the indexing model from the issue text.