Disable foot IK on pose playables and add ball pose

- PlayerPoseController: add applyFootIK toggle (default off) and apply it
  to each pose playable so straight-knee idles render straight; Mecanim
  foot IK was bending the knees to plant the feet (162° instead of 180°).
- Add Pose_Ball / Paintman-Ball animation and reorder the pose list.
- Move StraightenKneesTool editor utility under Assets/Unused/Editor.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scenes/SampleScene.unity

@@ -2213,12 +2213,14 @@ MonoBehaviour:
   poseSaveId: 
   poses:
   - {fileID: 11400000, guid: 3b59c882f27d0d04a82d2db251af1728, type: 2}
-  - {fileID: 11400000, guid: 1545cfba9b5e06d41ae72c7ec766baaf, type: 2}
   - {fileID: 11400000, guid: 649ecccdabb7ef9438addcec6663b037, type: 2}
+  - {fileID: 11400000, guid: 1545cfba9b5e06d41ae72c7ec766baaf, type: 2}
+  - {fileID: 11400000, guid: c5cf9d420554e5e4e96d3bee1903967a, type: 2}
   defaultPoseIndex: 0
   cycleKey: 17
   poseBlendDuration: 0.2
   ceilingOffsetSpeed: 4
+  applyFootIK: 0
 --- !u!114 &1141039644
 MonoBehaviour:
   m_ObjectHideFlags: 0