fix(vagrant): iteration — body+head look-at, WASD-driven leg-facing, idle-collapse

- humanoid.rig.json: root removed from upper track; body look_at + slow speed
  (180 deg/s, lazy); head fast speed (480 deg/s) + +-90 deg limits; puppet
  dep bumped to 0.3.1
- animations/idle_lower.anim.json (NEW): leg+foot scl=[mirror, 0] keeps legs
  invisible at idle (locomotion skips animated bones; foot cascade zeros out)
- init.lua: set_procedural 'facing' callback writes root.rot from
  last_walk_rot_deg each frame; WASD-vector updates last_walk_rot_deg
  via atan(dx, -dy); idle_lower played parallel to idle, stopped during walk

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

manifest.module

@@ -15,7 +15,7 @@
         {"id": "lib-core.camera",                 "version": "0.3.0"},
         {"id": "lib-core.render",                 "version": "0.1.0"},
         {"id": "lib-core.maps",                   "version": "0.1.2"},
-        {"id": "lib-core.puppet",                 "version": "0.3.0"},
+        {"id": "lib-core.puppet",                 "version": "0.3.1"},
         {"id": "lib-asset.prototype-subterrain",  "version": "0.1.1"}
     ]
 }