ui: 删除新增员工弹窗的参保城市字段

参保城市由社保账户自动确定，无需单独显示。

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

frontend/src/pages/roster/modals.tsx

@@ -1035,7 +1035,6 @@ export function AddEmployeeModal({ onClose, onSubmit, loading, error }: {
           </div>
         )}
         <div className="grid grid-cols-4 gap-4">
-          <div><Label>参保城市</Label><div className="text-xs text-gray-600 py-1.5">{autoAccounts?.socialAccount?.city || form.city || '—'}</div><div className="text-xs text-gray-400">从社保账户自动继承</div></div>
           <div><Label>学历</Label><Select value={form.education} onChange={(e) => setForm({ ...form, education: e.target.value })}><option value="">未选择</option><option value="博士">博士</option><option value="硕士">硕士</option><option value="本科">本科</option><option value="大专">大专</option><option value="高中">高中</option><option value="其他">其他</option></Select></div>
         </div>
         {/* 社保公积金 */}