Polish mobile UX downloads and comments

lib/backend/models/post_comment.dart

@@ -0,0 +1,17 @@
+class PostComment {
+  const PostComment({
+    required this.id,
+    required this.postId,
+    required this.providerId,
+    required this.authorName,
+    required this.body,
+    required this.createdAt,
+  });
+
+  final String id;
+  final String postId;
+  final String providerId;
+  final String authorName;
+  final String body;
+  final DateTime createdAt;
+}