Custom mouse cursor: normal/paint/pipette with recorder-aware software mode

- CursorController: polls painter state in LateUpdate; paint cursor only
  while the brush preview decal actually draws (MeshPainter.BrushPreviewVisible),
  pipette while held/toggled, fallback to normal over UI (InputUtil.PointerOverUi)
- Auto ForceSoftware while Unity Recorder is recording (reflection into
  editor-only assembly, 0.5s poll, editor-only) so the cursor is captured;
  back to hardware cursor when recording stops
- 3 placeholder cursor PNGs (32x32, cursor import type) with per-cursor hotspots

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/Scripts/Components/MeshPainter/MeshPainter.cs

@@ -422,6 +422,8 @@ public partial class MeshPainter : MonoBehaviour
     private bool _rayHitsSaturated; // log-once: a saturated buffer can silently drop our own collider
 
     // --- preview overlay ---
+    /// <summary>True while the brush preview decal is actually drawn this frame (hover hits the paintable surface).</summary>
+    public bool BrushPreviewVisible { get; private set; }
     public Shader previewShader;             // optional; else Shader.Find("Hidden/MeshPaintPreview")
     private Material _previewMat;
     private Mesh _previewQuad;               // unit quad in the tangent plane (flat decal mode)
@@ -785,6 +787,7 @@ public partial class MeshPainter : MonoBehaviour
             // the same local space as the raycast hit and valid for skinned (baked) and static meshes.
             Mesh previewMesh = _collider ? _collider.sharedMesh : null;
             if (!previewMesh) return;
+            BrushPreviewVisible = true;
             Matrix4x4 m = transform.localToWorldMatrix;
             int sub = previewMesh.subMeshCount;
             for (int i = 0; i < sub; i++)
@@ -804,6 +807,7 @@ public partial class MeshPainter : MonoBehaviour
             frame.SetColumn(3, new Vector4(pos.x, pos.y, pos.z, 1f));
 
             Graphics.DrawMesh(_previewQuad, transform.localToWorldMatrix * frame, _previewMat, layer, paintCamera, 0);
+            BrushPreviewVisible = true;
         }
     }
 
@@ -811,6 +815,8 @@ public partial class MeshPainter : MonoBehaviour
 
     private void Update()
     {
+        BrushPreviewVisible = false; // set again below only when the decal really draws this frame
+
         if (!_setupValid) return;
 
         if (useGpu != _gpuActive) SwitchBackend(useGpu);