[Fix] Pass make check lint

[samzong]

What's changed?

• Replace constant fmt.Errorf calls with errors.New where required by lint.
• Wrap long help and test setup lines to satisfy the line-length check.
• Rename the prune table header from PR STATE to STATE to avoid duplicate wording.

Why

• Make the repository's canonical make check gate pass cleanly.

Verification

• make check
• git diff HEAD~1..HEAD --check