fix: 修复默认审批人和抄送人不显示的问题

- 确保在所有执行路径上都设置 defaultLoadedRef
- 将获取的默认数据保存到 sessionStorage
- 移除 useEffect 依赖，只在组件挂载时加载一次

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/business-trip/apply.tsx

@@ -89,23 +89,35 @@ export default function BusinessTripApply() {
   // 加载默认审批人和抄送人（仅在首次加载且没有草稿数据时）
   const defaultLoadedRef = useRef(false)
   useEffect(() => {
-    // 防止重复加载
-    if (defaultLoadedRef.current) return
-
     const loadDefaultApprovers = async () => {
+      // 防止重复加载
+      if (defaultLoadedRef.current) return
+
       // 如果已经有存储的草稿数据，不加载默认值
       if (sessionStorage.getItem('businessTripDraft')) {
+        defaultLoadedRef.current = true
         return
       }
       // 如果已经从选择页面返回，不加载默认值
       if (location.state?.fromSelection) {
+        defaultLoadedRef.current = true
         return
       }
-      // 如果已经有存储的人员数据，不加载默认值
-      if (sessionStorage.getItem('selectedApprovers') || sessionStorage.getItem('selectedCc')) {
+      // 如果已经有存储的人员数据，恢复但不标记为已加载（允许后续更新）
+      const storedApprovers = sessionStorage.getItem('selectedApprovers')
+      const storedCc = sessionStorage.getItem('selectedCc')
+      if (storedApprovers || storedCc) {
+        if (storedApprovers) {
+          setApprovers(JSON.parse(storedApprovers))
+        }
+        if (storedCc) {
+          setCcUsers(JSON.parse(storedCc))
+        }
+        defaultLoadedRef.current = true
         return
       }
 
+      // 从后端获取默认配置
       try {
         const defaultData = await businessTripApi.getDefaultApprovers()
         if (defaultData.approvers && defaultData.approvers.length > 0) {
@@ -116,14 +128,14 @@ export default function BusinessTripApply() {
           setCcUsers(defaultData.cc_users)
           sessionStorage.setItem('selectedCc', JSON.stringify(defaultData.cc_users))
         }
-        defaultLoadedRef.current = true
       } catch (error) {
         console.error('Failed to load default approvers:', error)
       }
+      defaultLoadedRef.current = true
     }
 
     loadDefaultApprovers()
-  }, [location.state?.fromSelection])
+  }, [])
 
   // 处理从选择页面返回的数据和草稿恢复
   useEffect(() => {

frontend/src/pages/business-trip/select-approver.tsx

@@ -54,11 +54,9 @@ export default function SelectUserPage() {
     if (storedData) {
       try {
         const parsed = JSON.parse(storedData)
-        if (parsed.length > 0) {
-          setSelectedUsers(parsed)
-          initialLoadedRef.current = true
-          return
-        }
+        setSelectedUsers(parsed)
+        initialLoadedRef.current = true
+        return
       } catch (e) {
         console.error('Failed to parse stored data:', e)
       }
@@ -71,6 +69,10 @@ export default function SelectUserPage() {
         ? (defaultData.approvers || [])
         : (defaultData.cc_users || [])
       setSelectedUsers(defaultUsers)
+      // 将默认数据也保存到 sessionStorage
+      if (defaultUsers.length > 0) {
+        sessionStorage.setItem(storageKey, JSON.stringify(defaultUsers))
+      }
     } catch (error: any) {
       console.error('Failed to load default approvers:', error)
       // 获取失败时设置为空数组