feat(gui): Migrate _render_history_window to imgui_window scope

src/gui_2.py

@@ -789,7 +789,7 @@ class App:
   if not self.show_windows.get('Undo/Redo History', False):
    return
 
-  exp, opened = imgui.begin("Undo/Redo History", self.show_windows['Undo/Redo History'])
+  with imgui_window("Undo/Redo History", self.show_windows['Undo/Redo History']) as (exp, opened):
    self.show_windows['Undo/Redo History'] = bool(opened)
    if exp:
     if imgui.button("Undo") and self.history.can_undo:
@@ -805,7 +805,6 @@ class App:
      imgui.text("No history available.")
     else:
      for i, entry in enumerate(reversed(history)):
-     # Actual index in undo stack
       actual_idx = len(history) - 1 - i
       desc = entry.get("description", "UI Change")
       ts = entry.get("timestamp", 0.0)
@@ -817,7 +816,6 @@ class App:
       if selected:
        self._handle_jump_to_history(actual_idx)
     imgui.end_child()
-  imgui.end()
 
  def _gui_func(self) -> None:
   self._render_custom_title_bar()