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/tests/personal-workbench-assistant.test.mjs

@@ -0,0 +1,17 @@
+import assert from 'node:assert/strict'
+import { readFileSync } from 'node:fs'
+import test from 'node:test'
+import { fileURLToPath } from 'node:url'
+
+const workbench = readFileSync(
+  fileURLToPath(new URL('../src/components/business/PersonalWorkbench.vue', import.meta.url)),
+  'utf8'
+)
+
+test('workbench assistant greets the current employee without the old helper tag', () => {
+  assert.doesNotMatch(workbench, /assistant-tag/)
+  assert.doesNotMatch(workbench, /AI 报销助手/)
+  assert.match(workbench, /嗨，\{\{ assistantGreetingName \}\}，描述费用或上传票据，AI 直接帮你判断怎么报/)
+  assert.match(workbench, /const assistantGreetingName = computed/)
+  assert.match(workbench, /user\.name/)
+})