feat: allow download downloaded mods

Author: std-microblock

src/celemod-ui/src/components/ModList.tsx

@@ -87,7 +87,7 @@ export const Mod = memo(
         <div className="operations">
           <Button
             onClick={async () => {
-              if (downloadTask || props.isInstalled) return;
+              if (downloadTask) return;
 
               const down = (name: string, fileid: string) => {
                 setDownloadTask(