fix(#2290): drop redundant async blocks around sync_tmpfiles spawn

hive-c0re/src/server.rs

@@ -217,7 +217,7 @@ async fn handle_spawn(coord: &Arc<Coordinator>, name: &str) -> Result<HostRespon
                 sha: None,
             });
             // Update tmpfiles.d so the new agent's dirs survive a reboot.
-            tokio::spawn(async { lifecycle::sync_tmpfiles().await });
+            tokio::spawn(lifecycle::sync_tmpfiles());
         }
         Err(e) => {
             // Roll back socket registration if container creation failed.