feat: 20260809 系统优化 - 全部28项问题修复(P0×6+P1×16+P2×6)

P0: 福利批量参保/离职证明下载防乱码/考勤模板合并Sheet/补卡修改/附件在线查看删除
P1: 分页pageSize修复/离职导出筛选/撤回删除草稿/加班费自动计算/考勤加班汇总/证据链异常详情/制度催办/模板导入Word/社保封顶保底/校验字段提示/职务字段/社保费用明细/弹窗防误关/身份证查重/证明员工下拉/培训批量
P2: 离职流程去重/社保基数覆盖输入/薪税入口改名/添加员工引导/绩效模板清理

frontend/src/pages/Contracts.tsx

@@ -61,6 +61,7 @@ export default function Contracts() {
       queryClient.invalidateQueries({ queryKey: ['roster'] })
       queryClient.invalidateQueries({ queryKey: ['dashboard'] })
       queryClient.invalidateQueries({ queryKey: ['roster-profile'] })
+      localStorage.removeItem('add-employee-draft')
       setShowAddModal(false)
     },
   })
@@ -219,6 +220,7 @@ function AddEmployeeModal({ open, onClose, onSubmit, loading, error }: {
   const [form, setForm] = useState({
     name: '',
     department: '',
+    position: '',
     hireDate: '',
     monthlySalary: '',
     gender: '男' as '男' | '女',
@@ -239,6 +241,7 @@ function AddEmployeeModal({ open, onClose, onSubmit, loading, error }: {
     const data: any = {
       name: form.name,
       department: form.department,
+      position: form.position || undefined,
       hireDate: new Date(form.hireDate).toISOString(),
       monthlySalary: form.monthlySalary,
       gender: form.gender,
@@ -282,14 +285,19 @@ function AddEmployeeModal({ open, onClose, onSubmit, loading, error }: {
         </div>
 
         <div className="grid grid-cols-2 gap-3">
+          <div>
+            <Label>职务/岗位</Label>
+            <Input value={form.position} onChange={(e) => setForm({ ...form, position: e.target.value })} placeholder="如：前端工程师" />
+          </div>
           <div>
             <Label>入职日期 *</Label>
             <Input type="date" value={form.hireDate} onChange={(e) => setForm({ ...form, hireDate: e.target.value })} />
           </div>
-          <div>
-            <Label>月工资 *</Label>
-            <Input type="number" value={form.monthlySalary} onChange={(e) => setForm({ ...form, monthlySalary: e.target.value })} placeholder="元" />
-          </div>
+        </div>
+
+        <div>
+          <Label>月工资 *</Label>
+          <Input type="number" value={form.monthlySalary} onChange={(e) => setForm({ ...form, monthlySalary: e.target.value })} placeholder="元" />
         </div>
 
         <div className="grid grid-cols-2 gap-3">