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

frontend/src/pages/Contracts.tsx

@@ -8,6 +8,7 @@ import Button from '../components/ui/Button'
 import { Input, Label, Select } from '../components/ui/Input'
 import Modal from '../components/ui/Modal'
 import EmptyState from '../components/ui/EmptyState'
+import Pagination from '../components/ui/Pagination'
 
 interface EmployeeItem {
   id: string
@@ -37,13 +38,14 @@ export default function Contracts() {
   const [filterDepartment, setFilterDepartment] = useState('')
   const [filterContractStatus, setFilterContractStatus] = useState('')
   const [page, setPage] = useState(1)
+  const [pageSize, setPageSize] = useState(20)
   const [showAddModal, setShowAddModal] = useState(false)
   const [selectedEmpId, setSelectedEmpId] = useState<string | null>(null)
 
   const { data, isLoading } = useQuery<EmployeeListResponse>({
-    queryKey: ['employees', search, filterDepartment, filterContractStatus, page],
+    queryKey: ['employees', search, filterDepartment, filterContractStatus, page, pageSize],
     queryFn: async () => {
-      const params: any = { search, page, pageSize: 20 }
+      const params: any = { search, page, pageSize }
       if (filterDepartment) params.department = filterDepartment
       if (filterContractStatus) params.contractStatus = filterContractStatus
       const res = await api.get('/roster', { params }) as any
@@ -181,23 +183,13 @@ export default function Contracts() {
             </div>
 
             {/* 分页 */}
-            {data.totalPages > 1 && (
-              <div className="flex items-center justify-center gap-2 mt-4">
-                <Button
-                  variant="secondary"
-                  size="sm"
-                  disabled={page === 1}
-                  onClick={() => setPage(p => p - 1)}
-                >上一页</Button>
-                <span className="text-xs text-gray-500">{page} / {data.totalPages}</span>
-                <Button
-                  variant="secondary"
-                  size="sm"
-                  disabled={page === data.totalPages}
-                  onClick={() => setPage(p => p + 1)}
-                >下一页</Button>
-              </div>
-            )}
+            <Pagination
+              page={page}
+              pageSize={pageSize}
+              total={data.total}
+              onPageChange={setPage}
+              onPageSizeChange={(s) => { setPageSize(s); setPage(1) }}
+            />
           </>
         )}
       </Card>