refactor(ffi): expose satscard stepwise wait via wait

[reez]

Description

This PR updates the SATSCARD FFI wait API to expose the card's existing one-second auth delay step directly, returning the remaining delay after each call. That lets clients render cooldown progress one second at a time instead of estimating locally.

The immediate motivation is SatsBuddy PR #139, which added a UI countdown for SATSCARD cooldown recovery during send/sign. That PR is good enough for now on the app side, and this PR is the upstream follow-up that exposes a cleaner stepwise primitive for that flow.

Notes to the reviewers

This is intentionally scoped to SATSCARD only for now, since that is the current consumer. If we want the same API on TAPSIGNER or SATSCHIP, that can follow in a separate PR.

Changelog notice

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

[reez]

rebase on #64 and pull in changes

[notmandatory]

After #64 should be able to just expose the existing auth_wait for ffi instead of adding the new function wait_step.

[notmandatory]

ACK c91b137

I'd prefer to have the same wait FFI function for all three cards but if you need this now go ahead and merge it. I don't mind doing a followup PR for the other card types.

[reez]

ACK c91b137

I'd prefer to have the same wait FFI function for all three cards but if you need this now go ahead and merge it. I don't mind doing a followup PR for the other card types.

PR updated to add satschip and tapsigner, in 2 new commits

[notmandatory]

ACK 492ae4c

Thanks for updating the other card types!