fix: count combined episodes

Jellyfin allows combined episodes, like `S01E01-E02`,
but seasons containing such episodes are only recognized
as `Partially Available`. This commit should fix that.

server/api/jellyfin.ts

@@ -38,6 +38,7 @@ export interface JellyfinLibraryItem {
   SeasonId?: string;
   SeasonName?: string;
   IndexNumber?: number;
+  IndexNumberEnd?: number;
   ParentIndexNumber?: number;
   MediaType: string;
 }