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/styles/components/playlist-edit-modal.css

@@ -216,7 +216,7 @@
   padding: 5px 12px;
   border-radius: var(--radius-sm);
   background: var(--bg-card);
-  border: 1px solid var(--border);
+  border: 1px solid var(--ctp-surface1);
   color: var(--text-secondary);
   font-size: 12px;
   font-weight: 600;
@@ -227,7 +227,7 @@
 .artist-ext-link:hover {
   background: var(--bg-hover);
   color: var(--text-primary);
-  border-color: var(--border-subtle);
+  border-color: var(--ctp-overlay0);
 }
 
 /* Bio section */