Refactor: extractSignatureBytes to use stringToByteVector and add tra…

[ak004]

Description

Refactor the extractSignatureBytes helper to use the existing internal::Utilities::stringToByteVector() function and add a trailing newline to TransactionUnitTests.cc for POSIX compliance.

Changes:

• Refactor extractSignatureBytes to use stringToByteVector()
• Add trailing newline to TransactionUnitTests.cc

Related issue(s)

Fixes #1227

Notes for reviewer

• No functional changes; behavior remains identical
• Changes are limited to helper function and test file formatting

Checklist

• Documented (code comments already updated)
• Tested (existing unit tests pass)

[github-actions]

Hey @ak004 👋 thanks for the PR!
I'm your friendly PR Helper Bot 🤖 and I'll be riding shotgun on this one, keeping track of your PR's status to help you get it approved and merged.

This comment updates automatically as you push changes -- think of it as your PR's live scoreboard!
Here's the latest:

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PR Checks

✅ DCO Sign-off -- All commits have valid sign-offs. Nice work!

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✅ GPG Signature -- All commits have verified GPG signatures. Locked and loaded!

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✅ Merge Conflicts -- No merge conflicts detected. Smooth sailing!

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✅ Issue Link -- Linked to #1227 (assigned to you).

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🎉 All checks passed! Your PR is ready for review. Great job!

[rwalworth]

LGTM! The refactored extractSignatureBytes looks clean - it's consistent with how the rest of the file uses stringToByteVector, and the early-return structure is a nice improvement over the pointer approach. Trailing newline fix is good too.

Running the workflows now and will get this merged once they pass.

Congratulations on your first contribution to the Hiero C++ SDK @ak004! 🎉 I noticed you worked through a signing issue on your first attempt - that's totally normal, and you handled it well. Welcome to the project, and don't hesitate to reach out if you have questions on future contributions!

[ak004]

Thanks, I really appreciate it! Glad everything looks good.

And yeah, the signing part took me a minute 😄 — but I’m excited to keep contributing!