style(contacts): stretch contact cards to full width (auto-fit grid)

- replace fixed 2/4-column contact-grid with repeat(auto-fit, minmax(0,1fr))
  so cards fill the row like mp-card (Activity) cards; stack on mobile

public/css/main.css

@@ -4363,13 +4363,7 @@ html[data-radius="strong"] .skill-task-card__solution {
 
 @media (min-width: 560px) {
   .contact-grid {
-    grid-template-columns: repeat(2, minmax(0, 1fr));
-  }
-}
-
-@media (min-width: 1024px) {
-  .contact-grid {
-    grid-template-columns: repeat(4, minmax(0, 1fr));
+    grid-template-columns: repeat(auto-fit, minmax(0, 1fr));
   }
 }