macOS: Update core surface size when config changes

macos/Sources/Ghostty/SurfaceScrollView.swift

@@ -129,7 +129,7 @@ class SurfaceScrollView: NSView {
         surfaceView.$derivedConfig
             .sink { [weak self] _ in
                 DispatchQueue.main.async { [weak self] in
-                    self?.synchronizeAppearance()
+                    self?.handleConfigChange()
                 }
             }
             .store(in: &cancellables)
@@ -233,6 +233,12 @@ class SurfaceScrollView: NSView {
         synchronizeCoreSurface()
     }
 
+    /// Handles config changes
+    private func handleConfigChange() {
+        synchronizeAppearance()
+        synchronizeCoreSurface()
+    }
+    
     /// Handles live scroll events (user actively dragging the scrollbar).
     ///
     /// Converts the current scroll position to a row number and sends a `scroll_to_row` action