feat(ffi): add satscard waitStep for auth delay progress

[reez]

Description

This PR adds a SATSCARD-only waitStep API to rust-cktap so clients can 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