26.1-snapshot-2 (baby mobs)

- [x] Entity textures were moved into per-entity directories
- [ ] Baby mobs have their own models now, maybe we can add an option to configure whether to render a down-scaled version of the adult animal (as before) or the new model once they are added

No source files or tests are named. Start by locating the baby-mob model and rendering entry points, then inspect how adult animals are currently down-scaled. Done means a configuration option selects either the down-scaled adult rendering or the new baby model when available, with both choices rendering correctly.

Written by the indexing model from the issue text.