Keep tree lists updated at all times.

This simplifies the compiler logic since an updated tree list was necessary at many stages (e.g. attach and keyframes resizing) and it will be anyway required when computing the mjSpec signature.

PiperOrigin-RevId: 740356447
Change-Id: I7f2ec25b27b8d4ca4364801c9a401c40c6d84569

src/user/user_model.h

@@ -334,9 +334,11 @@ class mjCModel : public mjCModel_, private mjSpec {
   // list of active plugins
   std::vector<std::pair<const mjpPlugin*, int>> active_plugins_;
 
+  // make lists of bodies and children
+  void MakeTreeLists(mjCBody* body = nullptr);
+
   // compile phases
   void TryCompile(mjModel*& m, mjData*& d, const mjVFS* vfs);
-  void MakeLists(mjCBody* body);        // make lists of bodies, geoms, joints, sites
   void SetNuser();                      // set nuser fields
   void IndexAssets(bool discard);       // convert asset names into indices
   void CheckEmptyNames();               // check empty names