Do not delete attached specs after compilation.

Also, copy them when copying the spec.

PiperOrigin-RevId: 688998464
Change-Id: I7229fd8032eafede582194ccf73ab4160fe06768

doc/APIreference/functions.rst

@@ -4139,6 +4139,15 @@ mjs_getSpec
 
 Get spec from body.
 
+.. _mjs_findSpec:
+
+mjs_findSpec
+~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_findSpec
+
+Find spec (model asset) by name.
+
 .. _mjs_findBody:
 
 mjs_findBody

doc/includes/references.h

@@ -3600,6 +3600,7 @@ mjsSkin* mjs_addSkin(mjSpec* s);
 mjsTexture* mjs_addTexture(mjSpec* s);
 mjsMaterial* mjs_addMaterial(mjSpec* s, mjsDefault* def);
 mjSpec* mjs_getSpec(mjsElement* element);
+mjSpec* mjs_findSpec(mjSpec* spec, const char* name);
 mjsBody* mjs_findBody(mjSpec* s, const char* name);
 mjsElement* mjs_findElement(mjSpec* s, mjtObj type, const char* name);
 mjsBody* mjs_findChild(mjsBody* body, const char* name);