fix: 调整提问导航悬浮索引到右侧居中

frontend-web/src/components/workspace/question-navigator.tsx

@@ -108,8 +108,9 @@ function readCollapsedPreference(): boolean {
  * content area, and pass the inset via `className` (e.g. `top-16 bottom-48
  * left-0 right-0`). The component measures its own width: when the side gutter
  * next to the centered message column is wide enough it floats an expandable
- * panel there; on narrower viewports it degrades to a small pill button that
- * opens a right-side drawer, so it never covers the chat body or input box.
+ * panel there, vertically centered in the available chat area; on narrower
+ * viewports it degrades to a small pill button that opens a right-side drawer,
+ * so it never covers the chat body or input box.
  */
 export function QuestionNavigator({
   messages,
@@ -240,7 +241,7 @@ export function QuestionNavigator({
       ref={rootRef}
       className={cn("pointer-events-none absolute z-20", className)}
     >
-      <div className="absolute inset-y-0 right-3 flex items-start justify-end">
+      <div className="absolute inset-y-0 right-3 flex items-center justify-end">
         {panelFits ? (
           collapsed ? (
             pillButton("展开问题导航", toggleCollapsed)