fix(PdfPreviewPage): 在组件卸载前清除刷新标记

添加onBeforeUnmount钩子清除sessionStorage中的刷新标记，防止状态残留

@@ -12,7 +12,7 @@
 </template>
 
 <script setup>
-import { computed, onMounted } from 'vue'
+import { computed, onMounted, onBeforeUnmount } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import PdfViewer from '@/components/ui/PdfViewer.vue'
 
@@ -60,6 +60,14 @@ onMounted(() => {
     window.location.reload()
   }
 })
+
+/**
+ * 组件卸载前清除刷新标记
+ */
+onBeforeUnmount(() => {
+  // 清除刷新标记，确保离开页面时清理状态
+  sessionStorage.removeItem('pdf-preview-refreshed')
+})
 </script>
 
 <style scoped>