Send message by default mid turn. queue messages by tab (#9077)

https://github.com/user-attachments/assets/03838730-4ddc-44df-a2c7-cb8ecda78660

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

@@ -42,6 +42,7 @@ mod model_overrides;
 mod model_tools;
 mod models_etag_responses;
 mod otel;
+mod pending_input;
 mod permissions_messages;
 mod prompt_caching;
 mod quota_exceeded;