fix: UI refinements for NowPlayingBar and QualityBadge

- Artwork preview only triggers on hover over artwork, not entire song-card
- Double song-card min-width (320px → 640px, max 700px)
- Reduce all control icons by 2px (18→16, 20→18, 22→20)
- Reduce control button sizes (32→30px, play 36→34px)
- QualityBadge: reduce text 1pt (9→8px, 10→9px), alpha 90%

static/mp3-player.svg

@@ -0,0 +1,2 @@
+<?xml version="1.0" standalone="no"?>
+<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="128" height="128" viewBox="0 0 24 24" id="Layer_1" data-name="Layer 1"><defs><style>.cls-1{fill:none;stroke:#020202;stroke-miterlimit:10;stroke-width:1.91px;}</style></defs><rect class="cls-1" x="5.32" y="1.5" width="13.36" height="21" rx="1.91"/><circle class="cls-1" cx="12" cy="16.77" r="2.86"/><rect class="cls-1" x="8.18" y="4.36" width="7.64" height="6.68"/></svg>