Fix: wheel over UI scrolls the list instead of zooming the camera

The orbit rig read the wheel unfiltered for zoom, so scrolling a paint-mode
scroll list also zoomed the camera. Gate the zoom behind a shared
InputUtil.PointerOverUi() helper (EventSystem raycast); MeshPainter's private
IsPointerOverUi() now delegates to the same helper (DRY).

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

Assets/Scripts/Components/Controller/ThirdPersonOrbitInput.cs

@@ -238,11 +238,13 @@ public class ThirdPersonOrbitInput : MonoBehaviour
 
             float scale = CurrentScale();
 
-            // Shift/Ctrl+wheel is reserved for the paint brush resize (MeshPainter) - but only in paint
-            // mode (PanEnabled), where the resize actually claims the wheel. Outside paint mode Shift is
-            // the sprint key, so the wheel must still zoom.
-            bool brushResizeClaimsWheel = PanEnabled && (InputUtil.ShiftHeld() || InputUtil.CtrlHeld());
-            float scroll = brushResizeClaimsWheel ? 0f : InputUtil.ReadScroll();
+            // The wheel belongs to the UI when the pointer is over an interactive element (e.g. a scroll
+            // list), so it scrolls the UI instead of zooming. Shift/Ctrl+wheel is likewise reserved for the
+            // paint brush resize (MeshPainter) - but only in paint mode (PanEnabled), where the resize
+            // actually claims the wheel; outside paint mode Shift is the sprint key, so the wheel must zoom.
+            bool wheelClaimed = InputUtil.PointerOverUi()
+                             || (PanEnabled && (InputUtil.ShiftHeld() || InputUtil.CtrlHeld()));
+            float scroll = wheelClaimed ? 0f : InputUtil.ReadScroll();
             if (!Mathf.Approximately(scroll, 0f))
             {
                 // One wheel notch = one zoom step (sign only, platform-independent). The step scales with

Assets/Scripts/Components/MeshPainter/MeshPainter.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using UnityEngine;
-using UnityEngine.EventSystems;
 #if ENABLE_INPUT_SYSTEM
 using UnityEngine.InputSystem;
 #endif
@@ -1123,11 +1122,7 @@ public partial class MeshPainter : MonoBehaviour
     }
 
     /// <summary>True if the pointer is currently over an interactive UI element (raycast target).</summary>
-    private static bool IsPointerOverUi()
-    {
-        var es = EventSystem.current;
-        return es && es.IsPointerOverGameObject();
-    }
+    private static bool IsPointerOverUi() => InputUtil.PointerOverUi();
 
     private void OnDestroy()
     {

Assets/Scripts/Helper/InputUtil.cs

@@ -1,4 +1,5 @@
 using UnityEngine;
+using UnityEngine.EventSystems;
 #if ENABLE_INPUT_SYSTEM
 using UnityEngine.InputSystem;
 #endif
@@ -40,6 +41,15 @@ public static class InputUtil
         Cursor.visible = !locked;
     }
 
+    /// <summary>True while the pointer is over an interactive UI element (a raycast target), so the
+    /// wheel/click belongs to the UI (e.g. a scroll list) and must not also zoom the camera or paint
+    /// the mesh behind it. False when no EventSystem exists.</summary>
+    public static bool PointerOverUi()
+    {
+        var es = EventSystem.current;
+        return es && es.IsPointerOverGameObject();
+    }
+
     public static bool ShiftHeld()
     {
 #if ENABLE_INPUT_SYSTEM