test(traq): add unit tests from PR #1516 with CI and style fixes

- Add traq/traq_test.go with tests for etagCacheTransport and isETagTargetPath
- Update traq/webhook_impl_test.go with calcHMACSHA1 and NewWebhook tests
- Fix missing trailing newlines (gofmt compliance)
- Fix unused-parameter lint errors (rename r to _ where request is not used)
- Remove data race in concurrent test by dropping unused counter
- Retain existing TestMessageLimit test

https://claude.ai/code/session_012eg3ckWYgZLjWaYPeVYXCz

Author: claude