feat(player): add current track to playlists

apps/web/src/widgets/PlayerBar.module.css

@@ -311,7 +311,9 @@ a.source:hover {
   .controls { gap: 2px; }
   .play, .icon { width: 44px; height: 44px; }
   .right { display: flex; gap: 0; }
-  .right > :not(.queueButton):not(.shareButton) { display: none; }
+  .right > :not(.queueButton):not(.shareButton):not(.playlistButton) { display: none; }
+  .error { position: absolute; bottom: calc(100% + 8px); left: 8px; right: 8px;
+    padding: 8px 12px; background: var(--surface3); border-radius: 10px; text-align: center; }
   .drawer, .drawerIsland { bottom: calc(144px + env(safe-area-inset-bottom, 0px));
     max-height: calc(100dvh - 180px - env(safe-area-inset-bottom, 0px)); }
 }

apps/web/src/widgets/PlayerBar.tsx

@@ -4,6 +4,7 @@ import { Link } from '@tanstack/react-router';
 import { useTranslation } from 'react-i18next';
 
 import { ArtistLinks, Cover } from '../entities/catalog';
+import { AddToPlaylist } from '../entities/playlists';
 import { usePlayer, usePlayerState } from '../player/context';
 import { formatDuration } from '../shared/lib/format';
 import { shareTrack } from '../shared/lib/share';
@@ -178,6 +179,7 @@ export function PlayerBar({ variant = 'bar' }: { variant?: 'bar' | 'island' }) {
       </div>
 
       <div className={s.right}>
+        <AddToPlaylist trackIds={[track.id]} compact className={cx(s.icon, s.playlistButton)} />
         <button type="button" className={cx(s.icon, s.shareButton)} aria-label={t('player.share')} title={t('player.share')} disabled={sharing} onClick={() => void share()}>
           <Icon src={shareIcon} size={20} />
         </button>