Disable proxy discovery for the hot test HTTP clients so nextest no longer
pays macOS system proxy lookup on repeated reqwest client creation.
Also keep the approved OAuth loopback cleanup and replace GitHub test key
generation with a checked-in PEM fixture.
Integrate twin-openai (fake OpenAI server) into the workspace and wire
it into the e2e_test macro so OpenAI tests can run without real API
credentials. The twin server starts in-process via OnceLock on first use
and provides per-test isolation through bearer-token namespacing.
Changes:
- Add Twin as default TestMode, replacing Off (gating now via #[ignore])
- Extend #[e2e_test] macro with `twin` requirement for twin-only,
live-only, and dual-mode (twin + live) test gating
- Add e2e_openai!() macro returning (base_url, api_key)
- Convert openai_complete and openai_gpt_5_3_codex_complete to dual-mode
- Add new openai_server_error twin-only test with scripted 500 error
- Standardize axum 0.8 as workspace dependency across all crates
- Relax twin-openai ResponsesRequest to accept unknown fields via flatten
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
