feat: 前端补齐批量上传、重新摘要入库与入库进度页

- api/documents.js: 新增 uploadBatch / reingest / taskList 封装
- Ingest.vue: 新增「批量上传」标签页，多文件逐项异步入库并展示结果
- Documents.vue: 文档操作列新增「重新摘要」按钮（读原文件→删旧→新任务）
- 新增 Tasks.vue 入库进度页：近期任务列表 + 2s 自动轮询 + 状态徽标
- 路由与菜单新增「入库进度」入口

frontend/src/layouts/MainLayout.vue

@@ -15,7 +15,8 @@ import {
   LogoutOutlined,
   DatabaseOutlined,
   ApiOutlined,
-  TeamOutlined
+  TeamOutlined,
+  ClockCircleOutlined
 } from '@ant-design/icons-vue'
 import { useAuthStore } from '@/stores/useAuthStore'
 import { changeMyPassword } from '@/api/auth'
@@ -39,6 +40,7 @@ const menuItems = computed(() => {
     { key: 'overview', icon: () => h(DashboardOutlined), label: '概览' },
     { key: 'documents', icon: () => h(FileTextOutlined), label: '文档管理' },
     { key: 'ingest', icon: () => h(UploadOutlined), label: '文档入库' },
+    { key: 'tasks', icon: () => h(ClockCircleOutlined), label: '入库进度' },
     { key: 'search', icon: () => h(SearchOutlined), label: '检索测试台' },
     { key: 'categories', icon: () => h(AppstoreOutlined), label: '类目列表' },
     { key: 'settings', icon: () => h(SettingOutlined), label: '设置' },