Include news text preview in Telegram notification

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/src/PnvPanel.Application/Admin/News/CreatePostCommandHandler.cs

@@ -26,7 +26,11 @@ public sealed class CreatePostCommandHandler(
             post.CreatedAt,
             cancellationToken
         );
-        await telegramNotifier.NotifyUsersNewsPublishedAsync(post.Title, cancellationToken);
+        await telegramNotifier.NotifyUsersNewsPublishedAsync(
+            post.Title,
+            post.Body,
+            cancellationToken
+        );
 
         return Result.Success(NewsPostDto.FromDomain(post));
     }