The minimal E2E in ci.yml was masking curl/SOCKS forwarding failures
with '|| true' and piping through 'head', so tunnel failures were
silently ignored and CI always reported success.
Changes:
- Remove '|| true' from the curl/SOCKS5 forwarding test
- Capture curl exit code and fail CI if non-zero
- Assert HTTP 200 status code from the response
- Assert response body contains expected HTTP server content
- Use cross-platform 'sed' instead of 'head -n -1' (BSD/macOS)
- Also unmask the HTTP target health check
- Preserve existing cross-platform cleanup trap and helpers