feat(desktop): add offline cache and verified app updates

Clean release notes in Android and desktop update dialogs. Persist downloaded audio and offline playback events per server and user; add desktop update checks, checksum verification and installer launch.

apps/web/src/entities/catalog.tsx

@@ -4,6 +4,7 @@ import { Link } from '@tanstack/react-router';
 import { useVirtualizer } from '@tanstack/react-virtual';
 import { Fragment, useRef, useState, type CSSProperties, type MouseEvent, type ReactNode } from 'react';
 import { AddToPlaylist } from './playlists';
+import { SaveOfflineButton } from '../features/desktop/DesktopFeatures';
 import { useTranslation } from 'react-i18next';
 
 import { useSession } from '../app/session';
@@ -218,6 +219,7 @@ export function TrackList({
           </Link>
         )}
         <span className={s.end} data-playlist-actions={actions ? true : undefined}>
+          {!actions && <SaveOfflineButton track={tr} compact />}
           {actions ? actions(tr, i) : <AddToPlaylist trackIds={[tr.id]} compact />}
           {disliked ? (
             <button