Files marked as viewed should lose the "review stamp" if agent changes them

If an agent makes a change to a file collapsed by marking it as viewed while responding to the review comments, it should no longer be marked as viewed.

It looks like right now the file is unfolded but the viewed checkbox remains checked:

<img width="2289" height="504" alt="Image" src="https://github.com/user-attachments/assets/bf8159c9-1ee7-4f1d-998c-1c22b14a16a5" />