perf(ui): isolate scroll shadow effects

packages/ui/src/components/multirun/ModelMultiSelect.tsx

@@ -152,7 +152,7 @@ export const ModelMultiSelect: React.FC<ModelMultiSelectProps> = ({
     // Find the nearest dialog or overflow ancestor to constrain within
     let container: HTMLElement | null = triggerRef.current.parentElement;
     while (container) {
-      if (container.getAttribute('role') === 'dialog' || container.hasAttribute('data-scroll-shadow')) {
+      if (container.matches('[role="dialog"], [data-scroll-shadow-scroller]')) {
         break;
       }
       const style = getComputedStyle(container);

packages/ui/src/components/multirun/MultiRunLauncher.tsx

@@ -447,7 +447,7 @@ export const MultiRunLauncher: React.FC<MultiRunLauncherProps> = ({
         </header>
       ) : null}
 
-      <ScrollShadow className="flex-1 min-h-0 overflow-auto" size={64} hideTopShadow>
+      <ScrollShadow viewportClassName="flex-1 min-h-0" className="flex-1 min-h-0 overflow-auto" size={64} hideTopShadow>
         <div className="mx-auto w-full max-w-2xl px-4 sm:px-6 py-5">
           <div className="flex flex-col gap-5">