## Summary
- Harden `NewN1NModel` to avoid panics when `http.DefaultTransport` is a
custom non-`*http.Transport` RoundTripper.
- Fallback to a safe transport (`ProxyFromEnvironment`) while preserving
existing pooling/timeout settings.
- Add `n1n_test.go` with coverage for name/factory plus
`TestN1NNewModelWithCustomDefaultTransport`.
Co-authored-by: Cursor <cursoragent@cursor.com>
