age-plugin-fido2prf migration to telesma-app/ctap

Hi! I am the developer of [telesma-app/ctap](https://github.com/telesma-app/ctap). It's a fully featured Go CTAP library. I support almost every CTAP 2.3 feature, including the draft `previewSign` extension from Yubico. It's completely cgo-free (yes, I also reimplemented a subset of `libusb`/`hidapi`). I started it a year ago and wrote most of it by hand, only recently I started using agents. Architecturally, I believe it turned out well. Maybe it's worth your look for a possible migration.

Start by reviewing the current age-plugin-fido2prf implementation and comparing its scope with telesma-app/ctap, including CTAP 2.3 and previewSign support. Establish the migration boundary and compatibility expectations before changing code; done means the plugin has a decided migration path without losing supported behavior.

Written by the indexing model from the issue text.