feat: 支付渠道每日限额（渠道维度全平台统计）

- config.ts：新增 MAX_DAILY_AMOUNT_ALIPAY/WXPAY/STRIPE（默认 alipay/wxpay 各 1w，stripe 不限）
- lib/order/limits.ts：getMethodDailyLimit + queryMethodLimits 共用工具，支持动态渠道兜底
- order/service.ts：createOrder 校验渠道限额，超限抛 METHOD_DAILY_LIMIT_EXCEEDED
- api/limits/route.ts：公开接口 GET /api/limits，返回各渠道今日用量/剩余/是否可用
- api/user/route.ts：config 响应中加入 methodLimits，前端一次请求即可获取限额状态
- PaymentForm.tsx：额度已满的渠道置灰 + 标注「今日额度已满」，无法选择
- pay/page.tsx：AppConfig 加 methodLimits，传给 PaymentForm，新增错误码映射

src/app/api/limits/route.ts

@@ -0,0 +1,31 @@
+import { NextResponse } from 'next/server';
+import { getEnv } from '@/lib/config';
+import { queryMethodLimits } from '@/lib/order/limits';
+
+/**
+ * GET /api/limits
+ * 返回各支付渠道今日限额使用情况，公开接口（无需鉴权）。
+ *
+ * Response:
+ * {
+ *   methods: {
+ *     alipay: { dailyLimit: 10000, used: 3500, remaining: 6500, available: true },
+ *     wxpay:  { dailyLimit: 10000, used: 10000, remaining: 0,    available: false },
+ *     stripe: { dailyLimit: 0,     used: 500,  remaining: null,  available: true }
+ *   },
+ *   resetAt: "2026-03-02T00:00:00.000Z"  // UTC 次日零点（限额重置时间）
+ * }
+ */
+export async function GET() {
+  const env = getEnv();
+  const types = env.ENABLED_PAYMENT_TYPES;
+
+  const todayStart = new Date();
+  todayStart.setUTCHours(0, 0, 0, 0);
+  const resetAt = new Date(todayStart);
+  resetAt.setUTCDate(resetAt.getUTCDate() + 1);
+
+  const methods = await queryMethodLimits(types);
+
+  return NextResponse.json({ methods, resetAt });
+}

src/app/api/user/route.ts

@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from 'next/server';
 import { getUser } from '@/lib/sub2api/client';
 import { getEnv } from '@/lib/config';
+import { queryMethodLimits } from '@/lib/order/limits';
 
 export async function GET(request: NextRequest) {
   const userId = Number(request.nextUrl.searchParams.get('user_id'));
@@ -10,7 +11,10 @@ export async function GET(request: NextRequest) {
 
   try {
     const env = getEnv();
-    const user = await getUser(userId);
+    const [user, methodLimits] = await Promise.all([
+      getUser(userId),
+      queryMethodLimits(env.ENABLED_PAYMENT_TYPES),
+    ]);
 
     return NextResponse.json({
       user: {
@@ -22,6 +26,7 @@ export async function GET(request: NextRequest) {
         minAmount: env.MIN_RECHARGE_AMOUNT,
         maxAmount: env.MAX_RECHARGE_AMOUNT,
         maxDailyAmount: env.MAX_DAILY_RECHARGE_AMOUNT,
+        methodLimits,
       },
     });
   } catch (error) {

src/app/pay/page.tsx

@@ -8,6 +8,7 @@ import OrderStatus from '@/components/OrderStatus';
 import PayPageLayout from '@/components/PayPageLayout';
 import MobileOrderList from '@/components/MobileOrderList';
 import { detectDeviceIsMobile, type UserInfo, type MyOrder } from '@/lib/pay-utils';
+import type { MethodLimitInfo } from '@/components/PaymentForm';
 
 interface OrderResult {
   orderId: string;
@@ -25,6 +26,7 @@ interface AppConfig {
   minAmount: number;
   maxAmount: number;
   maxDailyAmount: number;
+  methodLimits?: Record<string, MethodLimitInfo>;
 }
 
 function PayContent() {
@@ -54,7 +56,7 @@ function PayContent() {
   const [config, setConfig] = useState<AppConfig>({
     enabledPaymentTypes: ['alipay', 'wxpay', 'stripe'],
     minAmount: 1,
-    maxAmount: 10000,
+    maxAmount: 1000,
     maxDailyAmount: 0,
   });
 
@@ -90,7 +92,13 @@ function PayContent() {
       if (cfgRes.ok) {
         const cfgData = await cfgRes.json();
         if (cfgData.config) {
-          setConfig(cfgData.config);
+          setConfig({
+            enabledPaymentTypes: cfgData.config.enabledPaymentTypes ?? ['alipay', 'wxpay'],
+            minAmount: cfgData.config.minAmount ?? 1,
+            maxAmount: cfgData.config.maxAmount ?? 1000,
+            maxDailyAmount: cfgData.config.maxDailyAmount ?? 0,
+            methodLimits: cfgData.config.methodLimits,
+          });
         }
       }
 
@@ -212,6 +220,7 @@ function PayContent() {
           TOO_MANY_PENDING: '您有过多待支付订单，请先完成或取消现有订单后再试',
           USER_NOT_FOUND: '用户不存在，请检查链接是否正确',
           DAILY_LIMIT_EXCEEDED: data.error,
+          METHOD_DAILY_LIMIT_EXCEEDED: data.error,
           PAYMENT_GATEWAY_ERROR: data.error,
         };
         setError(codeMessages[data.code] || data.error || '创建订单失败');
@@ -350,6 +359,7 @@ function PayContent() {
                 userName={userInfo?.username}
                 userBalance={userInfo?.balance}
                 enabledPaymentTypes={config.enabledPaymentTypes}
+                methodLimits={config.methodLimits}
                 minAmount={config.minAmount}
                 maxAmount={config.maxAmount}
                 onSubmit={handleSubmit}