Side-by-side terminal layout is not restored when switching Agent sessions

Type: Bug

When multiple terminals belonging to an Agent session are arranged side by side, switching to another session in the Agents window and then switching back restores the terminal instances, but not their split layout.

## Steps to reproduce

1. Open an Agent session in the Agents window.
2. Create at least two terminals for that session.
3. Arrange the terminals side by side using a split terminal layout.
4. Switch to a different Agent session in the Agents window.
5. Switch back to the original session.

## Expected behavior

The terminals and their side-by-side split layout are restored as they were before switching sessions.

## Actual behavior

The terminals are restored, but they are no longer shown side by side; the split layout is lost.