Fix POST endpoint URL in proxy stream

server/src/main.rs

@@ -156,7 +156,7 @@ async fn sse_handler(
     
     state.clients.write().unwrap().insert(session_id.clone(), tx.clone());
     
-    let _ = tx.send(Ok(Event::default().event("endpoint").data(format!("?sessionId={}", session_id)))).await;
+    let _ = tx.send(Ok(Event::default().event("endpoint").data(format!("/messages?sessionId={}", session_id)))).await;
     
     let stream = ReceiverStream::new(rx);
     Sse::new(stream).keep_alive(axum::response::sse::KeepAlive::new())