Fixed

• The genre filter was mostly just showing "Audiobook." Genre tags weren't being cleaned enough：plenty of real Audible/Libation exports tag genre as a :-joined category breadcrumb ("Science Fiction & Fantasy:Science Fiction:Adventure"), which came through as one unsplit string, and — the actual complaint — a large share of real files tag genre as literally nothing but "Audiobook" (the file format, not what the book is about), which dominated the dropdown as if it were a genre choice. Genre extraction now also splits on : and drops a short list of medium-not-genre values ("Audiobook", "Audio Book", and case/spacing variants), so the dropdown reflects real literary genres — Fantasy, Horror, Mystery, Sci-Fi, and so on — instead. This applies retroactively to libraries scanned before this fix, no rescan needed.