Update HUD panel layout and reorder brush masks in scene

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

Assets/Scenes/SampleScene.unity

@@ -1425,8 +1425,8 @@ MonoBehaviour:
   emissionIntensity: 20
   brushSize: 50
   brushMasks:
-  - {fileID: 10300, guid: 0000000000000000f000000000000000, type: 0}
   - {fileID: 10912, guid: 0000000000000000f000000000000000, type: 0}
+  - {fileID: 10300, guid: 0000000000000000f000000000000000, type: 0}
   activeBrushIndex: 0
   brushAlignment: 0
   brushRotation: 0