fix(library): a listing poll can no longer put back an older resume point

A poll already out when the player closed answered with the point the server held before the
closing beacon, over the row's patch; Continue then opened there and wrote it back. The close now
cancels the listings' fetches before patching and reads them again once the beacon has landed.

frontend/src/lib/api/downloads.ts

@@ -299,11 +299,16 @@ export const downloadsApi = {
     id: number,
     positionSeconds: number,
     durationSeconds: number,
+    onSettled?: () => void,
   ): void =>
-    beacon(`/api/downloads/${id}/progress`, {
-      position_seconds: Math.floor(positionSeconds),
-      duration_seconds: Math.floor(durationSeconds),
-    }),
+    beacon(
+      `/api/downloads/${id}/progress`,
+      {
+        position_seconds: Math.floor(positionSeconds),
+        duration_seconds: Math.floor(durationSeconds),
+      },
+      onSettled,
+    ),
   // A plain <a> navigation can't send the X-Siftlode-Account header, so pass the active
   // account via ?account= (the server honours it only for an account in this browser's wallet) —
   // otherwise the download resolves to the session-default account and 404s for a per-tab