fix: 合并 useEffect 逻辑，修复默认审批人不显示的问题

问题原因：两个 useEffect 执行顺序冲突
- 第一个 useEffect 加载默认数据
- 第二个 useEffect 又清除了人员数据

解决方案：合并为一个统一的 useEffect，按优先级处理：
1. 从选择页面返回 -> 恢复 sessionStorage 数据
2. 有草稿数据 -> 恢复草稿及关联人员数据
3. 首次进入 -> 清除旧数据，加载默认配置

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

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

@@ -86,40 +86,89 @@ export default function BusinessTripApply() {
   // 使用 ref 来跟踪是否已经恢复过草稿
   const hasRestoredRef = useRef(false)
 
-  // 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)
+  // 统一处理：草稿恢复、默认审批人加载、选择页面返回
+  const initRef = useRef(false)
   useEffect(() => {
+    // 防止重复执行
+    if (initRef.current) {
+      // 只有从选择页面返回时才重新执行
+      if (!location.state?.fromSelection) {
+        return
+      }
+    }
+
+    const fromSelection = location.state?.fromSelection
+    console.log('📍 Page init:', { fromSelection, path: location.pathname })
+
+    // 1. 从选择页面返回：恢复所有人员数据
+    if (fromSelection) {
+      console.log('🔄 Returning from selection page')
+      const approversData = sessionStorage.getItem('selectedApprovers')
+      if (approversData) {
+        const approvers = JSON.parse(approversData) as ApproverItem[]
+        setApprovers(approvers)
+        console.log('✅ Restored approvers:', approvers)
+      } else {
+        setApprovers([])
+      }
+
+      const ccData = sessionStorage.getItem('selectedCc')
+      if (ccData) {
+        const cc = JSON.parse(ccData) as ApproverItem[]
+        setCcUsers(cc)
+        console.log('✅ Restored CC:', cc)
+      } else {
+        setCcUsers([])
+      }
+      initRef.current = true
+      return
+    }
+
+    // 2. 恢复草稿数据（理由、行程）
+    const draftData = sessionStorage.getItem('businessTripDraft')
+    if (draftData) {
+      console.log('📦 Restoring draft data')
+      try {
+        const draft = JSON.parse(draftData)
+        if (draft.reason) setReason(draft.reason)
+        if (draft.itineraries && draft.itineraries.length > 0) {
+          const restoredItineraries = draft.itineraries.map((item: any) => ({
+            ...item,
+            startTime: item.startTime ? new Date(item.startTime) : null,
+            endTime: item.endTime ? new Date(item.endTime) : null,
+          }))
+          setItineraries(restoredItineraries)
+        }
+      } catch (error) {
+        console.error('❌ Failed to restore draft:', error)
+      }
+    }
+
+    // 3. 加载默认审批人和抄送人（仅在首次且无草稿时）
     const loadDefaultApprovers = async () => {
-      // 防止重复加载
-      if (defaultLoadedRef.current) return
+      if (initRef.current) return
+      initRef.current = true
 
-      // 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，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
+      // 如果有草稿数据，不加载默认值
+      if (draftData) {
+        console.log('⏭️ Skipping default load (has draft)')
+        // 恢复草稿关联的人员数据
+        const approversData = sessionStorage.getItem('selectedApprovers')
+        const ccData = sessionStorage.getItem('selectedCc')
+        if (approversData) setApprovers(JSON.parse(approversData))
+        if (ccData) setCcUsers(JSON.parse(ccData))
         return
       }
 
-      // 从后端获取默认配置
+      // 清除旧数据，加载默认配置
+      console.log('🔄 Loading default approvers from backend...')
+      sessionStorage.removeItem('selectedApprovers')
+      sessionStorage.removeItem('selectedCc')
+
       try {
         const defaultData = await businessTripApi.getDefaultApprovers()
+        console.log('✅ Default approvers:', defaultData)
+
         if (defaultData.approvers && defaultData.approvers.length > 0) {
           setApprovers(defaultData.approvers)
           sessionStorage.setItem('selectedApprovers', JSON.stringify(defaultData.approvers))
@@ -129,107 +178,12 @@ export default function BusinessTripApply() {
           sessionStorage.setItem('selectedCc', JSON.stringify(defaultData.cc_users))
         }
       } catch (error) {
-        console.error('Failed to load default approvers:', error)
+        console.error('❌ Failed to load default approvers:', error)
       }
-      defaultLoadedRef.current = true
     }
 
     loadDefaultApprovers()
-  }, [])
-
-  // 处理从选择页面返回的数据和草稿恢复
-  useEffect(() => {
-    const fromSelection = location.state?.fromSelection
-
-    console.log('📍 Page loaded/updated:', {
-      fromSelection,
-      path: location.pathname
-    })
-
-    // 恢复草稿数据（每次组件挂载都需要恢复）
-    const draftData = sessionStorage.getItem('businessTripDraft')
-    console.log('📦 Draft data in sessionStorage:', draftData)
-
-    if (draftData) {
-      try {
-        const draft = JSON.parse(draftData)
-        console.log('📄 Parsed draft:', draft)
-
-        // 恢复理由
-        if (draft.reason) {
-          console.log('✏️ Restoring reason:', draft.reason)
-          setReason(draft.reason)
-        }
-
-        // 恢复行程数据
-        if (draft.itineraries && draft.itineraries.length > 0) {
-          const restoredItineraries = draft.itineraries.map((item: any) => ({
-            ...item,
-            startTime: item.startTime ? new Date(item.startTime) : null,
-            endTime: item.endTime ? new Date(item.endTime) : null,
-          }))
-          console.log('🛤️ Restoring itineraries:', restoredItineraries)
-          setItineraries(restoredItineraries)
-        }
-
-        // 有草稿数据，也尝试恢复人员数据
-        if (!fromSelection) {
-          const approversData = sessionStorage.getItem('selectedApprovers')
-          if (approversData) {
-            const approvers = JSON.parse(approversData) as ApproverItem[]
-            setApprovers(approvers)
-            console.log('✅ Restored approvers (with draft):', approvers)
-          }
-
-          const ccData = sessionStorage.getItem('selectedCc')
-          if (ccData) {
-            const cc = JSON.parse(ccData) as ApproverItem[]
-            setCcUsers(cc)
-            console.log('✅ Restored CC (with draft):', cc)
-          }
-        }
-      } catch (error) {
-        console.error('❌ Failed to restore draft:', error)
-      }
-    } else {
-      console.log('⚠️ No draft data found in sessionStorage')
-      // 没有草稿数据，清除旧的人员选择数据（开始新申请）
-      if (!fromSelection) {
-        console.log('🧹 Clearing old selection data (new application)')
-        sessionStorage.removeItem('selectedApprovers')
-        sessionStorage.removeItem('selectedCc')
-        setApprovers([])
-        setCcUsers([])
-      }
-    }
-
-    // 从选择页面返回，恢复所有人员数据
-    if (fromSelection) {
-      console.log('🔄 Returning from selection page')
-
-      const type = location.state?.type
-      console.log('📋 Selection type:', type)
-
-      // 恢复所有人员数据（审批人 + 抄送人）
-      const approversData = sessionStorage.getItem('selectedApprovers')
-      if (approversData) {
-        const approvers = JSON.parse(approversData) as ApproverItem[]
-        setApprovers(approvers)
-        console.log('✅ Restored approvers from sessionStorage:', approvers)
-      } else {
-        setApprovers([])
-      }
-
-      const ccData = sessionStorage.getItem('selectedCc')
-      if (ccData) {
-        const cc = JSON.parse(ccData) as ApproverItem[]
-        setCcUsers(cc)
-        console.log('✅ Restored CC from sessionStorage:', cc)
-      } else {
-        setCcUsers([])
-      }
-    }
-  }, [location.state, location.pathname])
+  }, [location.state])
 
   // 计算总时长（累加所有行程的天数）
   const totalDuration = useMemo(() => {