fix(pr168): title→data-tooltip, i18n playlist toggle, cold-start playlist fetch

- Replace title= with data-tooltip on sidebar playlist expand button (CLAUDE.md)
- Replace hardcoded Spanish aria-label strings with i18n keys (sidebar.expandPlaylists / collapsePlaylists) across all 8 locales
- AddToPlaylistSubmenu now fetches playlists on first open if store is empty (regression fix)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/ContextMenu.tsx

@@ -49,6 +49,13 @@ export function AddToPlaylistSubmenu({ songIds, onDone, dropDown, triggerId }: {
   const recentIds = usePlaylistStore((s) => s.recentIds);
   const createPlaylist = usePlaylistStore((s) => s.createPlaylist);
   const touchPlaylist = usePlaylistStore((s) => s.touchPlaylist);
+  const fetchPlaylists = usePlaylistStore((s) => s.fetchPlaylists);
+
+  // Fetch playlists on first open if the store hasn't been populated yet
+  useEffect(() => {
+    if (storePlaylists.length === 0) fetchPlaylists();
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
 
   // Sort playlists by recent usage
   const playlists = useMemo(() => {

src/components/Sidebar.tsx

@@ -250,8 +250,8 @@ export default function Sidebar({
                     className={`sidebar-playlists-toggle ${playlistsExpanded ? 'expanded' : ''}`}
                     onClick={() => setPlaylistsExpanded(!playlistsExpanded)}
                     aria-expanded={playlistsExpanded}
-                    aria-label={playlistsExpanded ? 'Colapsar listas' : 'Expandir listas'}
-                    title={playlistsExpanded ? 'Colapsar listas' : 'Expandir listas'}
+                    aria-label={playlistsExpanded ? t('sidebar.collapsePlaylists') : t('sidebar.expandPlaylists')}
+                    data-tooltip={playlistsExpanded ? t('sidebar.collapsePlaylists') : t('sidebar.expandPlaylists')}
                   >
                     <ChevronRight size={14} />
                   </button>