在并发的 `RouteList::generate` 期间,当 `Resource` 首次进行轮询时,SSR 渲染会永久挂起(全局 `SuppressResourceLoad` 进程)

Describe the bug

If a Resource's future is first polled while any other thread in the process is inside RouteList::generate (route-list generation / SSG), that resource — and the SSR render awaiting it — hangs forever, even though the generation window closes shortly afterwards.