feat: 完善报销单审批流程及退回原因追踪

新增直属领导审批通过接口和审批待办列表查询，报销单退回
支持原因码分类和审批环节标记，优化票据附件去重和路径
回退查找，前端新增退回原因对话框、审批收件箱和工作台
图标组件，补充工具函数和单元测试覆盖。

web/src/utils/approvalInbox.js

@@ -0,0 +1,40 @@
+import { mapExpenseClaimToRequest } from '../composables/useRequests.js'
+import { canManageExpenseClaims } from './accessControl.js'
+
+export function canProcessApprovalRequest(request, currentUser) {
+  const node = String(request?.workflowNode || '').trim()
+  const currentName = String(currentUser?.name || '').trim()
+  const applicantName = String(request?.person || request?.employeeName || '').trim()
+
+  if (currentName && applicantName && currentName === applicantName) {
+    return false
+  }
+
+  if (canManageExpenseClaims(currentUser)) {
+    return true
+  }
+
+  return (
+    node.includes('直属领导')
+    || node.includes('领导审批')
+    || node.includes('部门负责人')
+    || node.includes('负责人审批')
+  )
+}
+
+export function listPendingApprovalRequests(claimsPayload, currentUser) {
+  if (!Array.isArray(claimsPayload)) {
+    return []
+  }
+
+  return claimsPayload
+    .map((item) => mapExpenseClaimToRequest(item))
+    .filter((item) => item.approvalKey === 'in_progress')
+    .filter((item) => canProcessApprovalRequest(item, currentUser))
+}
+
+export function resolvePendingClaimIds(claimsPayload, currentUser) {
+  return listPendingApprovalRequests(claimsPayload, currentUser)
+    .map((item) => String(item.claimId || '').trim())
+    .filter(Boolean)
+}