Fix sgl-router startup crash

sgl-router/src/router.rs

@@ -180,7 +180,13 @@ impl Router {
             }
             _ => {
                 // Wait until all workers are healthy for regular modes
-                Self::wait_for_healthy_workers(&worker_urls, timeout_secs, interval_secs)?;
+                let worker_urls = worker_urls.clone();
+                std::thread::spawn(move || {
+                    // If the function returns Result<_, String> keep it, otherwise adjust
+                    Self::wait_for_healthy_workers(&worker_urls, timeout_secs, interval_secs)
+                })
+                .join()
+                .map_err(|e| format!("Health-check thread panicked: {e:?}"))??;
             }
         }