refactor(export): remove scroll back-to-top affordance

src/pages/ExportPage.tsx

@@ -1275,7 +1275,6 @@ function ExportPage() {
   const [hasSeededSnsStats, setHasSeededSnsStats] = useState(false)
   const [nowTick, setNowTick] = useState(Date.now())
   const [isContactsListAtTop, setIsContactsListAtTop] = useState(true)
-  const [isPageScrolled, setIsPageScrolled] = useState(false)
   const tabCounts = useContactTypeCountsStore(state => state.tabCounts)
   const isSharedTabCountsLoading = useContactTypeCountsStore(state => state.isLoading)
   const isSharedTabCountsReady = useContactTypeCountsStore(state => state.isReady)
@@ -1596,19 +1595,6 @@ function ExportPage() {
     return () => clearInterval(timer)
   }, [isExportRoute])
 
-  useEffect(() => {
-    if (!isExportRoute) {
-      setIsPageScrolled(false)
-      return
-    }
-    const onWindowScroll = () => {
-      setIsPageScrolled(window.scrollY > 160)
-    }
-    onWindowScroll()
-    window.addEventListener('scroll', onWindowScroll, { passive: true })
-    return () => window.removeEventListener('scroll', onWindowScroll)
-  }, [isExportRoute])
-
   useEffect(() => {
     if (!isTaskCenterOpen || !expandedPerfTaskId) return
     const target = tasks.find(task => task.id === expandedPerfTaskId)
@@ -3810,7 +3796,6 @@ function ExportPage() {
   const taskRunningCount = tasks.filter(task => task.status === 'running').length
   const taskQueuedCount = tasks.filter(task => task.status === 'queued').length
   const hasFilteredContacts = filteredContacts.length > 0
-  const showBackToTop = isPageScrolled || !isContactsListAtTop
   const closeTaskCenter = useCallback(() => {
     setIsTaskCenterOpen(false)
     setExpandedPerfTaskId(null)
@@ -3923,10 +3908,6 @@ function ExportPage() {
     showSessionDetailPanel,
     toggleSelectSession
   ])
-  const handleBackToTop = useCallback(() => {
-    contactsVirtuosoRef.current?.scrollToIndex({ index: 0, align: 'start', behavior: 'smooth' })
-    window.scrollTo({ top: 0, behavior: 'smooth' })
-  }, [])
   const handleContactsListWheelCapture = useCallback((event: WheelEvent<HTMLDivElement>) => {
     const deltaY = event.deltaY
     if (!deltaY) return
@@ -4563,16 +4544,6 @@ function ExportPage() {
         </div>
       </div>
 
-      {showBackToTop && (
-        <button
-          type="button"
-          className="back-to-top-btn"
-          onClick={handleBackToTop}
-        >
-          回到顶部
-        </button>
-      )}
-
       {exportDialog.open && createPortal(
         <div className="export-dialog-overlay" onClick={closeExportDialog}>
           <div className="export-dialog" role="dialog" aria-modal="true" onClick={(event) => event.stopPropagation()}>