Unify dock leaves around single-tab stacks

new_editor/src/Shell/UIEditorWorkspaceLayoutPersistence.cpp

@@ -391,7 +391,7 @@ UIEditorWorkspaceLayoutSnapshot BuildUIEditorWorkspaceLayoutSnapshot(
     const UIEditorWorkspaceModel& workspace,
     const UIEditorWorkspaceSession& session) {
     UIEditorWorkspaceLayoutSnapshot snapshot = {};
-    snapshot.workspace = workspace;
+    snapshot.workspace = CanonicalizeUIEditorWorkspaceModel(workspace);
     snapshot.session = session;
     return snapshot;
 }
@@ -461,6 +461,8 @@ UIEditorWorkspaceLayoutLoadResult DeserializeUIEditorWorkspaceLayoutSnapshot(
         return rootResult;
     }
 
+    snapshot.workspace = CanonicalizeUIEditorWorkspaceModel(std::move(snapshot.workspace));
+
     snapshot.session.panelStates.clear();
     while (index < lines.size()) {
         UIEditorPanelSessionState state = {};