Cull off-screen children in scroll containers

Skip render command generation for elements whose bounding box
falls entirely outside their parent scroll container's clip bounds,
reducing render commands for large scrollable content.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: andreakarasho

src/Clay/Core/ClayContext.cs

@@ -1111,14 +1111,24 @@ private void GenerateRenderCommandsRecursive(int elementIndex, short zIndex, Bou
 
         var boundingBox = hashItem.BoundingBox;
 
-        // Culling
+        // Culling against viewport
         if (!CullingDisabled)
         {
             if (boundingBox.Right < 0 || boundingBox.Bottom < 0 ||
                 boundingBox.X > LayoutDimensions.Width || boundingBox.Y > LayoutDimensions.Height)
             {
                 return;
             }
+
+            // Culling against scroll container clip bounds
+            if (hasClip)
+            {
+                if (boundingBox.Right < clipBounds.X || boundingBox.Bottom < clipBounds.Y ||
+                    boundingBox.X > clipBounds.Right || boundingBox.Y > clipBounds.Bottom)
+                {
+                    return;
+                }
+            }
         }
 
         // Find configs
@@ -1187,6 +1197,17 @@ private void GenerateRenderCommandsRecursive(int elementIndex, short zIndex, Bou
                 childHashItem.HasClipBounds = childHasClip;
                 childHashItem.ClipBounds = childClip;
 
+                // Cull text elements outside scroll container bounds
+                if (!CullingDisabled && childHasClip)
+                {
+                    var childBox = childHashItem.BoundingBox;
+                    if (childBox.Right < childClip.X || childBox.Bottom < childClip.Y ||
+                        childBox.X > childClip.Right || childBox.Y > childClip.Bottom)
+                    {
+                        continue;
+                    }
+                }
+
                 int textConfigIndex = FindConfigIndex(ref child, ElementConfigType.Text);
                 if (textConfigIndex < 0) continue;