Harper can block file saving

**Describe the bug**

In very big files, Harper can block file saving for multiple seconds. But why is that even the case as Harper doesn't provide any formatter?

**To Reproduce**
Steps to reproduce the behavior:
1. Save a big file

**Expected behavior**
Harper doesn't run on file save.

**Screenshots**

**Platform**
Cursor, MacOS

Start by reproducing the delay in Cursor on macOS by saving a very large file, then trace the save integration to determine why Harper runs during saving. Done means saving a large file no longer blocks for multiple seconds because Harper is not invoked on file save.

Written by the indexing model from the issue text.