fix: draw a focused tag's ring above the next tag

The focus ring reaches farther than the gap between tags, and the next tag painted over its right side.

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

website/static/style.css

@@ -1243,6 +1243,11 @@ th[data-sort].sort-asc::after {
   margin-left: 0.2rem;
 }
 
+/* The focus ring reaches past the gap, so lift it above the next tag */
+.tag:focus-visible {
+  z-index: 1;
+}
+
 /* A 44px-tall target centered on the pill, kept clear of the neighbouring tags */
 .tag::after {
   content: "";