Refactor: extractSignatureBytes to use stringToByteVector and add tra…

[ak004]

Description:

Refactor the extractSignatureBytes helper function to use internal::Utilities::stringToByteVector instead of manually converting strings to byte vectors.
Also, add a trailing newline at the end of TransactionUnitTests.cc

• Use stringToByteVector for consistency
• Add newline to TransactionUnitTests.cc

Related issue(s):

Fixes #1227

Notes for reviewer:

This is a refactor and formatting change only — no behavior or API changes.

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[github-actions]

Hey @ak004 👋 thanks for the PR!
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• 260ed02 Refactor: extractSignatureBytes to use stringToByteVector and add trailing newline

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

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