Import IKAR messenger client and server

test/channel_comments_test.dart

@@ -0,0 +1,20 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:ikar/core/utils/channel_comments.dart';
+
+void main() {
+  group('commentsInfoBatches', () {
+    test('splits long histories into bounded requests', () {
+      final ids = [for (var i = 0; i < 120; i++) '$i'];
+      final batches = commentsInfoBatches(ids);
+      expect(batches.map((b) => b.length), [50, 50, 20]);
+      expect(batches.expand((b) => b).toList(), ids);
+    });
+
+    test('short lists stay in one request', () {
+      expect(commentsInfoBatches(['1', '2']), [
+        ['1', '2'],
+      ]);
+      expect(commentsInfoBatches(const []), isEmpty);
+    });
+  });
+}