API cleanup

[notmandatory]

Description

Notes to the reviewers

The original purpose of this was to simplify the API as much as possible by only returning required data from commands instead of the entire APDU message which contains fields only needed for validation or to update the nonce. Along the way I realized the generics can be removed which makes the FFI bindings easier to do and generally simplifies the code. I also cleaned up some other warnings and dependencies.

I added lib sign and sign_psbt commands for SatsCard and refactored errors for all commands to be more tailored to what could actually go wrong. I also added "sign <psbt>" and "dump <slot>" commands to the cli for SatsCard, and exposed all lib commands and errors in the FFI bindings.

Changelog notice

• Reduced data returned from most commands to just what is needed
• Fixed warnings
• Add lib sign and sign_psbt functions for SatsCard
• Refactored lib errors to be more tailored to the commands
• Add cli "sign <psbt>" and "dump <slot>" commands for SatsCard
• Expanded FFI bindings to all available lib commands and errors
• Added top level Justfile

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[notmandatory]

@reez I'm going to need your help figuring out how to test the FFI bindings with Swift to exercise the new CkTransport trait.

[reez]

@reez I'm going to need your help figuring out how to test the FFI bindings with Swift to exercise the new CkTransport trait.

Cool, let's take a look at this together tomorrow!

[reez]

Tested local bindings and made version + address call successfully ✅

[notmandatory]

I also had some success today and got my Swift test working with a custom CkTransport that talks to a locally running card emulator. So now I should be able to move on to adding the rest of the APIs to the ffi bindings.

[notmandatory]

Got SATSCARD sign and sign_psbt functions working with emulator unit test and with a real card on mainnet. I used bdk-cli to construct my PSBT, signed it with the rust-cktap cli and my SATSCARD, then finalized and broadcast it with the bdk-cli.

cc: @praveenperera

[notmandatory]

I should be all done with refactoring and exposing all implemented card commands via ffi. The nfc and xpub commands still need to be implemented but can do in follow-up PRs.