Grid Multi-Body: Enable Cross-Window SubGrid Detachment (Pop-out)

As part of the Multi-Body Grid architecture, we need to ensure that the Left (locked: 'start') and Right (locked: 'end') SubGrids can be detached from the main window and rendered in separate popup windows, similar to the LivePreview component.

Requirements:

1. Encapsulation: SubGrids must be fully functional even when not physically adjacent in the same DOM tree.
2. Window Connect/Disconnect Logic: Implement logic (likely on the Grid Container) to handle moving a SubGrid instance into a newly spawned window and recovering it when the window closes.
3. Data Continuity: Ensure the App Worker maintains the single source of truth for the Store and SelectionModel regardless of which window the VDOM is projected into.