remove thumbnail cache

app/models/cache.ts

@@ -2,16 +2,12 @@ import { Album, Playlist, Artist, Song } from './library'
 
 export enum CacheItemType {
   coverArt = 'coverArt',
-  coverArtThumb = 'coverArtThumb',
   artistArt = 'artistArt',
-  artistArtThumb = 'artistArtThumb',
   song = 'song',
 }
 
 export type CacheItemTypeKey = keyof typeof CacheItemType
 
-export type CacheImageSize = 'thumbnail' | 'original'
-
 export type CacheFile = {
   path: string
   date: number