fix(ui): reserve the pointer cursor for the update chip

Extension cards no longer show a pointer cursor on hover; the tappable
update status chip shows it instead, on cards and detail headers alike.

ui/flutter/lib/features/extensions/presentation/widgets/extension_update_status.dart

@@ -35,12 +35,15 @@ class ExtensionUpdateStatus extends StatelessWidget {
       ],
     );
     if (onTap == null) return content;
-    return GestureDetector(
-      behavior: HitTestBehavior.opaque,
-      onTap: onTap,
-      child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 6),
-        child: content,
+    return MouseRegion(
+      cursor: SystemMouseCursors.click,
+      child: GestureDetector(
+        behavior: HitTestBehavior.opaque,
+        onTap: onTap,
+        child: Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 6),
+          child: content,
+        ),
       ),
     );
   }