fix: artist hero banner shows face/upper body on desktop

background-position: center crops to mid-body on wide desktop banners.
Shifting to center 20% anchors the crop in the upper-third of the image
where faces typically are, matching the phone experience.

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

src/views/detail.js

@@ -108,7 +108,7 @@ export async function loadArtistDetail(artist) {
   // ── Hero ──
   const img = imgRes.status === 'fulfilled' ? imgRes.value : null;
   if(img) {
-    hero.style.background = `url('${img}') center/cover no-repeat`;
+    hero.style.background = `url('${img}') center 20%/cover no-repeat`;
     if(overlay) overlay.style.background = 'linear-gradient(to right,rgba(7,7,15,.95) 0%,rgba(7,7,15,.35) 55%,rgba(7,7,15,.75) 100%)';
   }