💄 style(UI): standardize scrollbar styling for semi-sidesheet-body

Standardize the scrollbar appearance of semi-sidesheet-body to match the existing semi-table-body style. This change:
- Sets scrollbar width to 6px
- Applies light gray color (rgba(var(--semi-grey-2), 0.3))
- Adds subtle hover effect
- Uses 2px border radius for consistency
- Improves overall UI cohesion across components

web/src/index.css

@@ -358,6 +358,25 @@ code {
   background: transparent;
 }
 
+/* 侧边抽屉滚动条样式 */
+.semi-sidesheet-body::-webkit-scrollbar {
+  width: 6px;
+  height: 6px;
+}
+
+.semi-sidesheet-body::-webkit-scrollbar-thumb {
+  background: rgba(var(--semi-grey-2), 0.3);
+  border-radius: 2px;
+}
+
+.semi-sidesheet-body::-webkit-scrollbar-thumb:hover {
+  background: rgba(var(--semi-grey-2), 0.5);
+}
+
+.semi-sidesheet-body::-webkit-scrollbar-track {
+  background: transparent;
+}
+
 /* 隐藏模型设置区域的滚动条 */
 .model-settings-scroll::-webkit-scrollbar,
 .thinking-content-scroll::-webkit-scrollbar,