fix(admin): prevent false partner commission cap errors

Coerce city maxPartnerCommissionRate to Number so Decimal JSON strings do not break sum checks.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/admin-web/src/pages/CityPartnersPage.tsx

@@ -98,9 +98,12 @@ function flattenDistrictCodes(values: string[] | string[][] | undefined): string
 }
 
 function commissionSumError(orderPercent: number, redeemPercent: number, maxRate: number): string | null {
-  const sum = orderPercent / 100 + redeemPercent / 100;
-  if (sum > maxRate + 1e-9) {
-    return `订单佣金与核销佣金合计不得超过 ${(maxRate * 100).toFixed(2)}%（当前 ${(sum * 100).toFixed(2)}%）`;
+  // API 可能把 Prisma Decimal 序列化为字符串；`"0.05" + 1e-9` 会变成字符串拼接导致误判超限
+  const max = Number(maxRate);
+  const sum = Number(orderPercent) / 100 + Number(redeemPercent) / 100;
+  if (!Number.isFinite(max) || !Number.isFinite(sum)) return '佣金比例无效';
+  if (sum > max + 1e-9) {
+    return `订单佣金与核销佣金合计不得超过 ${(max * 100).toFixed(2)}%（当前 ${(sum * 100).toFixed(2)}%）`;
   }
   return null;
 }
@@ -149,7 +152,7 @@ export default function CityPartnersPage() {
     const d = await request<PartnerDetail>(`/admin/partners/${id}`);
     setDetail(d);
     setEditScopeType((d.scopeType as CityPartnerScopeType) || CityPartnerScopeType.CITY_WIDE);
-    setMaxCommissionRate(d.maxPartnerCommissionRate ?? 0.05);
+    setMaxCommissionRate(Number(d.maxPartnerCommissionRate ?? 0.05));
     editForm.setFieldsValue({
       name: d.name,
       phone: d.phone,
@@ -230,7 +233,7 @@ export default function CityPartnersPage() {
 
   async function onCreateCityChange(cityId: string) {
     const cityRes = await request<{ maxPartnerCommissionRate?: number }>(`/admin/cities/${cityId}`);
-    setCreateMaxRate(cityRes.maxPartnerCommissionRate ?? 0.05);
+    setCreateMaxRate(Number(cityRes.maxPartnerCommissionRate ?? 0.05));
   }
 
   const columns: ColumnsType<Row> = [