feat(web): activity indicator while loading

web/src/components/ActivityIndicator.jsx

@@ -0,0 +1,15 @@
+import { h } from 'preact';
+
+const sizes = {
+  sm: 'h-4 w-4 border-2 border-t-2',
+  md: 'h-8 w-8 border-4 border-t-4',
+  lg: 'h-16 w-16 border-8 border-t-8',
+};
+
+export default function ActivityIndicator({ size = 'md' }) {
+  return (
+    <div className="w-full flex items-center justify-center" aria-label="Loading…">
+      <div className={`activityindicator ease-in rounded-full border-gray-200 text-blue-500 ${sizes[size]}`} />
+    </div>
+  );
+}