Wait for requested delay in rate limit errors (#2266)

Fixes: https://github.com/openai/codex/issues/2131

Response doesn't have the delay in a separate field (yet) so parse the
message.

codex-rs/core/src/chat_completions.rs

@@ -213,7 +213,9 @@ async fn process_chat_sse<S>(
         let sse = match timeout(idle_timeout, stream.next()).await {
             Ok(Some(Ok(ev))) => ev,
             Ok(Some(Err(e))) => {
-                let _ = tx_event.send(Err(CodexErr::Stream(e.to_string()))).await;
+                let _ = tx_event
+                    .send(Err(CodexErr::Stream(e.to_string(), None)))
+                    .await;
                 return;
             }
             Ok(None) => {
@@ -228,7 +230,10 @@ async fn process_chat_sse<S>(
             }
             Err(_) => {
                 let _ = tx_event
-                    .send(Err(CodexErr::Stream("idle timeout waiting for SSE".into())))
+                    .send(Err(CodexErr::Stream(
+                        "idle timeout waiting for SSE".into(),
+                        None,
+                    )))
                     .await;
                 return;
             }