fix(artist-detail): Last.fm/Wikipedia/Favorite hover keeps button border (#966)

* fix(artist-detail): keep ext-link border visible on hover

Hover used --border-subtle, which on Catppuccin matches --bg-card and
visually erased the rim while only the fill changed. Match btn-surface:
--ctp-surface1 border, --ctp-overlay0 on hover.

* docs(changelog): credit zunoz on Psysonic Discord for PR #966

* fix(playlists): tooltips on Play/Add Songs and song count pluralization

Add data-tooltip to Play and Add Songs in playlist hero; switch
playlists.songs to count-based _one/_other forms (was {{n}} without
i18next plural suffix, breaking spacing and singular).

* fix(playlists): render BPM and optional cols in Suggested Songs rows

PlaylistSuggestions shared column headers with the main tracklist but
its row switch omitted bpm, genre, playCount, and lastPlayed.

src/components/playlists/PlaylistCard.tsx

@@ -161,7 +161,7 @@ export default function PlaylistCard({
           <span>{displayPlaylistName(pl.name)}</span>
         </div>
         <div className="album-card-artist">
-          {t('playlists.songs', { n: filteredSongCountByPlaylist[pl.id] ?? pl.songCount })}
+          {t('playlists.songs', { count: filteredSongCountByPlaylist[pl.id] ?? pl.songCount })}
           {(filteredDurationByPlaylist[pl.id] ?? pl.duration) > 0 && (
             <> · {formatHumanHoursMinutes(filteredDurationByPlaylist[pl.id] ?? pl.duration)}</>
           )}