Keep selected card in view when opening preview

Opening the preview panel narrows .grid-area and reflows the auto-fill grid
to fewer columns, moving the clicked card to a new row. The single-frame
scrollIntoView ran while the browser's scroll-anchoring re-adjusted scrollTop
mid-reflow, so the card scrolled out of view. Disable scroll anchoring on
.grid-area (overflow-anchor:none) and defer the scroll by two animation
frames against the settled layout, centring the card (block:'center').

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

static/style.css

@@ -197,7 +197,7 @@
   .filter-clear:hover { border-color: var(--danger); color: var(--danger); }
 
   /* Grid */
-  .grid-area { flex: 1; overflow-y: auto; padding: 24px; min-width: 0; scrollbar-width: thin; scrollbar-color: var(--border) transparent; }
+  .grid-area { flex: 1; overflow-y: auto; overflow-anchor: none; padding: 24px; min-width: 0; scrollbar-width: thin; scrollbar-color: var(--border) transparent; }
   .grid-area::-webkit-scrollbar { width: 4px; }
   .grid-area::-webkit-scrollbar-track { background: transparent; }
   .grid-area::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }