perf(components): 优化 ScrollBar 组件性能

- 将 createMemo 改为 createEffect，减少不必要的计算
- 优化 thumbPos 计算逻辑，提高滚动性能
- 调整 setIsDragging 调用方式，确保正确更新状态

src/components/ScrollArea.tsx

@@ -2,6 +2,7 @@ import cx from 'clsx';
 import { clamp } from 'es-toolkit';
 import {
   Component,
+  createEffect,
   createMemo,
   createSignal,
   JSX,
@@ -27,9 +28,9 @@ const ScrollBar: Component<ScrollBarProps> = (props) => {
   const [thumbPos, setThumbPos] = createSignal(0);
   const [isDragging, setIsDragging] = createSignal(false);
 
-  const thumbPos = createMemo(() => {
+  createEffect(() => {
     if (props.scrollMax <= 0) {
-      return 0;
+      setThumbPos(0);
     }
 
     const scrollPercent = props.scrollPos / props.scrollMax;
@@ -37,10 +38,11 @@ const ScrollBar: Component<ScrollBarProps> = (props) => {
     const trackSize = props.axis === 'y' ? track.clientHeight : track.clientWidth;
 
     if (trackSize < thumbSize) {
-      return 0;
+      setThumbPos(0);
     }
 
-    return scrollPercent * (trackSize - thumbSize);
+    const pos = scrollPercent * (trackSize - thumbSize);
+    setThumbPos(pos);
   });
   const thumbStyle = createMemo(() => ({
     [props.axis === 'y' ? 'top' : 'left']: `${thumbPos()}px`,