feat: 全部列表页统一分页 + WorkProcess集成现有服务

- WorkProcess/Termination/Evidence/Contracts/Policies/Templates 添加 Pagination 组件
- 后端 getDrafts/getPolicies/enterprise-template 路由添加分页支持（可选参数，向后兼容）
- work-process.service CONFIRM case 修正：移除不存在的 probationEndDate 字段
- 新增 migration_add_three_tables.sql 增量迁移文件

backend/src/routes/policy.routes.ts

@@ -13,8 +13,10 @@ const router = Router()
 router.get('/', authMiddleware, async (req: AuthRequest, res: Response, next: NextFunction) => {
   try {
     const status = req.query.status as string | undefined
-    const policies = await getPolicies(req.user!.orgId, status)
-    res.json({ success: true, data: policies })
+    const page = parseInt(req.query.page as string) || 1
+    const pageSize = Math.min(parseInt(req.query.pageSize as string) || 20, 200)
+    const result = await getPolicies(req.user!.orgId, status, page, pageSize)
+    res.json({ success: true, data: result })
   } catch (err) {
     next(err)
   }