[BUG] Undo replaces Dynamic Choice with Assign after stack shift

[matKlju]

Bug description:
When adding an Assign node followed by a Dynamic Choice node, then performing undo three times (where the first undo shifts the entire stack), adding a new Dynamic Choice and undoing again causes the Dynamic Choice node to be substituted with an Assign node.

Expected behavior:
Undo/redo should restore the correct node types and state. A Dynamic Choice node must remain a Dynamic Choice after undo, without being replaced by an Assign node.

Screenshots:
on first undo:

second undo:

third undo (after adding Dynamic Choice):

Additional information:
Repro steps:

1. Add Assign
2. Add Dynamic Choice
3. Undo twice
   • on first undo, the whole stack shifts
   • second undo
4. Add Dynamic Choice
5. Third Undo

Result:

• Second undo shifts stack
• Dynamic Choice is replaced by Assign

[matKlju]

AT passed - works as expected!