Center pills within the reserved tag zone

Single-row pill cards now sit centered in the two-row zone instead of pinned to
the top, so they balance visually against two-row cards. Titles already aligned;
this aligns the pills themselves.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/ArticleCard.svelte

@@ -107,7 +107,7 @@
      across the grid, whether a card has 1, 2, or 3 tags. A hairline closes
      the zone. (The hero is its own layout and opts out.) */
   .tile .tags {
-    align-items: flex-start; align-content: flex-start;
+    align-items: center; align-content: center;
     min-height: 48px; padding-bottom: 11px; margin-bottom: 2px;
     border-bottom: 1px solid var(--line);
   }