Investigate intermittent CI Unit Tests failure on main (run 22137863252)

[joelklabo]

Observed in GitHub Actions CI run https://github.com/joelklabo/nostrstack/actions/runs/22137863252

• Workflow: CI
• Branch: main
• Failed job: Unit Tests
• Annotation: Process completed with exit code 1

Local pre-commit run for issue #130 passed all API unit tests (24 files / 114 tests), so this may be intermittent/flaky or environment-specific.

Follow-up:

1. Pull full failing logs for job 63994145341.
2. Identify deterministic repro or classify as infra/flake.
3. Add stabilization or retries only if root cause is external.