Gate transaction builder tests in CI

[takemiyamakoto]

Summary

• run the transaction-builder coverage audit in GitHub Actions before the simulator build
• run the same audit pair in scripts/ci/run-pr.sh before dependency and Xcode work

Validation

• bash scripts/test-transaction-builder-tests-audit.sh
• bash scripts/audit-transaction-builder-tests.sh
• bash -n scripts/ci/run-pr.sh scripts/test-transaction-builder-tests-audit.sh scripts/audit-transaction-builder-tests.sh
• git diff --check

Release note

This keeps transaction-builder coverage from being dropped from iOS PR validation or CI while the wallet support matrix continues to expand.