fix: refactor and improve bip322 tests, remove unused functions

[victorkirov]

🔘 PR Type

What kind of change does this PR introduce?

• Refactoring (no functional changes, no api changes)

📜 Background

Our test didn't actually validate that the bip322 signing function was working, and the additional verify method caused confusion in the main bip322 file as it was test-related only.

🔄 Changes

Does this PR introduce a breaking change?

• No, Bug fixes (backwards compatible)

Changes:

• Message signing was cleaned up and better tested
• No changes to code that is being used

✅ Review checklist

Please ensure the following are true before merging:

• Code Style is consistent with the project guidelines.
• Code is readable and well-commented.
• No unnecessary or debugging code has been added.
• Security considerations have been taken into account.
• The change has been manually tested and works as expected.
• Breaking changes and their impacts have been considered and documented.
• Code does not introduce new technical debt or issues.

[github-actions]

Test this PR with npm i @secretkeylabs/[email protected]