fix: guard bill generation submission

apps/admin/src/pages/Bills/index.tsx

@@ -89,9 +89,11 @@ const BillsPage: React.FC = () => {
   }, [bills, searchText, filterStatus]);
 
   const handleGenerate = async () => {
-    setSaving(true);
-    const values = await generateForm.validateFields();
+    if (saving) return;
+
     try {
+      const values = await generateForm.validateFields();
+      setSaving(true);
       const res: any = await api.post('/bills/generate', {
         periodStart: values.period[0].format('YYYY-MM-DD'),
         periodEnd: values.period[1].format('YYYY-MM-DD'),
@@ -99,9 +101,12 @@ const BillsPage: React.FC = () => {
       message.success(res.message || '生成成功');
       setGenerateModal(false);
       generateForm.resetFields();
-      fetchData();
+      void fetchData();
     } catch (e: any) {
-      message.error(e?.message || '生成失败');
+      // Ant Design 的表单校验失败会 reject；字段本身已展示错误，无需再弹“生成失败”。
+      if (!e?.errorFields) {
+        message.error(e?.message || '生成失败');
+      }
     } finally {
       setSaving(false);
     }