Refresh on models etag mismatch (#8491)

- Send models etag
- Refresh models on 412
- This wires `ModelsManager` to `ModelFamily` so we don't mutate it
mid-turn

codex-rs/core/tests/suite/mod.rs

@@ -37,6 +37,7 @@ mod list_models;
 mod live_cli;
 mod model_overrides;
 mod model_tools;
+mod models_etag_responses;
 mod otel;
 mod prompt_caching;
 mod quota_exceeded;