Define card utility classes and fix equal-height grid cards

Previously grid-equal-height, card-full-height, card-content-stretch, and
card-hover were all undefined class names doing nothing. Now defined:

- .grid-equal-height > * { height: 100% } — forces every grid child to fill
  its row height, making adjacent cards stretch to match the tallest sibling
- .card-full-height { h-full } — card fills its wrapper
- .card-content-stretch { flex-1 } — CardContent grows to push footer down
- .card-hover — subtle shadow + ring lift on hover

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

src/styles/globals.css

@@ -109,6 +109,29 @@
   }
 }
 
+.card-hover {
+  @apply transition-all duration-200 hover:shadow-lg hover:ring-foreground/20;
+}
+
+/* grid-equal-height: force every direct child to fill the row */
+.grid-equal-height > * {
+  height: 100%;
+}
+
+/* card-full-height: card fills its wrapper */
+.card-full-height {
+  @apply h-full;
+}
+
+/* card-content-stretch: CardContent grows to push footer content down */
+.card-content-stretch {
+  @apply flex-1;
+}
+
+.sidebar-contact-link {
+  @apply rounded-lg;
+}
+
 @keyframes fade-in-up {
   from { opacity: 0; transform: translateY(10px); }
   to { opacity: 1; transform: translateY(0); }