PROJECT: Adapt LetheKit for SeedSigner

- [ ] Review Issue
- [ ] Create Subtasks
- [ ] Determine if LetheKit Needs to Be Updated

[LetheKit v0](https://github.com/BlockchainCommons/lethekit) is an open source DIY hardware box with offline cryptographic tools. It can use dice for entropy, import seeds in a variety formats, and exports derived keys using UR-based QR codes.

However, it can't support crypto-request QRs, or sign transactions as it does not have a camera.

[SeedSigner](https://github.com/seedsigner/seedsigner/) is another open source DIY device that does have a camera and a better display but it does not support UR QRs.

The goal would be to evaluate if we can submit patches to @seedsigner to add all the UR functionality that LetheKit has, and if not, port the LetheKit code to that hardware as an alternative to the seedsigner code base.

Sub-projects could be to understand requirements (for instance, LetheKit forgets when powered off, I'm not sure with seedsigner) and use cases, evaluate their code, update the existing LetheKit v0 code for recent UR features, write docs, create a video tutorial, update the LetheKit web page, etc.

Suitable as a possible internship project. See [Discussion](https://github.com/BlockchainCommons/Community/discussions/76#discussioncomment-2382520)

@ksedgwic or @gorazdko, fomer leads on LetheKit project might be persuaded to be mentors.