Disable Nagle's algorithm for code-mode WebSockets (#37504)

## Why

Code-mode WebSocket connections are latency-sensitive, so buffering small TCP
writes can delay request and response traffic.

## What changed

- Enable `TCP_NODELAY` on outbound remote-session WebSocket connections.
- Enable `TCP_NODELAY` on sockets accepted by the code-mode host, logging a
  warning if the socket option cannot be set.

## Testing

- Add a listener test that connects to the host and verifies the accepted
  socket has `TCP_NODELAY` enabled.

GitOrigin-RevId: e51c781c4b47c6a4ae1c32c93cd79768719a68d9

codex-rs/code-mode/src/remote_session/connection.rs

@@ -656,11 +656,13 @@ async fn connect_websocket_transport(
             "failed to build code-mode host websocket request: {error}"
         ))
     })?;
-    let connector = WebSocketConnector::new(http_client_factory).map_err(|error| {
-        ConnectionError::Other(format!(
-            "failed to configure code-mode host websocket TLS: {error}"
-        ))
-    })?;
+    let connector = WebSocketConnector::new(http_client_factory)
+        .map_err(|error| {
+            ConnectionError::Other(format!(
+                "failed to configure code-mode host websocket TLS: {error}"
+            ))
+        })?
+        .with_tcp_nodelay();
     let websocket_config = WebSocketConfig::default()
         .max_frame_size(Some(MAX_WEBSOCKET_FRAME_BYTES))
         .max_message_size(Some(MAX_WEBSOCKET_FRAME_BYTES));