[DEFECT] Layout editor changes making unexpected changes to pre-existing content on the page

Problem Statement

layout editor changes and re-orders of rows causes content to shift containers or disappear completely from edit mode.

Steps to Reproduce

Video Screencast:

https://github.com/user-attachments/assets/b66fa99e-63a3-42de-b1f1-9475ac080935

1. Create a new page or copy an existing page on the current evergreen version. Add content in at least three containers and in one container use both the system container and the default container - maybe banner in the top full row, then activity content in a 60/40 row underneath that. Save and Publish.
2. Edit the layout of the page, and add a new row both above and below the bottom row and add the default container again to both of them. Do not wait for the default saving to finish before adding the rows, work quickly as I do in the video.
3. Go back to the content view on the page and see if content either disappears or switches position on the page.

Acceptance Criteria

Regardless of how fast the edits are made on the layout view, the view that is present when clicking back to the content view should be respected and content should stay in the container it was placed in originally. Containers should not shift positions when new rows are added to the layout editor.

dotCMS Version

Latest Evergreen on demo.dotcms.com: 25.12.16-01

Severity

Medium - Some functionality impacted

FreshDesk Support Ticket

https://dotcms.freshdesk.com/a/tickets/34279

Start by reproducing the race in the layout editor using the listed steps and the attached screencast, then compare the layout editor with the page content view after rapid row and container changes. Done means existing content remains in its original containers and positions regardless of edit speed; the issue names no source files or tests, so those must be located from the editor entry point.