Add pageIndex on infinite query results

- Result selector runs on every page on every fetch, which means that the uniqueId is not immutable. We need a static index on each item since a playlist can have duplicate song ids

src/renderer/features/playlists/queries/playlist-song-list-query.ts

@@ -49,8 +49,8 @@ export const usePlaylistSongListInfinite = (
       (data: InfiniteData<RawSongListResponse | undefined>) => {
         return {
           ...data,
-          pages: data.pages.map((page) => {
-            return api.normalize.songList(page, server);
+          pages: data.pages.map((page, index) => {
+            return { ...api.normalize.songList(page, server), pageIndex: index };
           }),
         };
       },