feat: 每日充值限额 + 单笔上限默认 1000 + 前端金额校验优化

- 新增 MAX_DAILY_RECHARGE_AMOUNT 环境变量（0=不限制），
  创建订单时统计当日已付款总额，超限返回友好提示
- MAX_RECHARGE_AMOUNT 默认值从 10000 改为 1000
- PaymentForm 快速金额按钮过滤掉超过 maxAmount 的选项
- 金额超限时前端显示明确提示（单笔最低/最高 ¥xxx）
- 支付说明栏展示每日限额信息

src/app/api/user/route.ts

@@ -21,6 +21,7 @@ export async function GET(request: NextRequest) {
         enabledPaymentTypes: env.ENABLED_PAYMENT_TYPES,
         minAmount: env.MIN_RECHARGE_AMOUNT,
         maxAmount: env.MAX_RECHARGE_AMOUNT,
+        maxDailyAmount: env.MAX_DAILY_RECHARGE_AMOUNT,
       },
     });
   } catch (error) {

src/app/pay/page.tsx

@@ -24,6 +24,7 @@ interface AppConfig {
   enabledPaymentTypes: string[];
   minAmount: number;
   maxAmount: number;
+  maxDailyAmount: number;
 }
 
 function PayContent() {
@@ -51,6 +52,7 @@ function PayContent() {
     enabledPaymentTypes: ['alipay', 'wxpay', 'stripe'],
     minAmount: 1,
     maxAmount: 10000,
+    maxDailyAmount: 0,
   });
 
   const effectiveUserId = resolvedUserId || userId;
@@ -178,6 +180,7 @@ function PayContent() {
           USER_INACTIVE: '账户已被禁用，无法充值，请联系管理员',
           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,
         };
         setError(codeMessages[data.code] || data.error || '创建订单失败');
         return;
@@ -349,6 +352,9 @@ function PayContent() {
                   <ul className={['mt-2 space-y-1 text-sm', isDark ? 'text-slate-300' : 'text-slate-600'].join(' ')}>
                     <li>订单完成后会自动到账</li>
                     <li>如需历史记录请查看"我的订单"</li>
+                    {config.maxDailyAmount > 0 && (
+                      <li>每日最大充值 ¥{config.maxDailyAmount.toFixed(2)}</li>
+                    )}
                     {!hasToken && <li className={isDark ? 'text-amber-200' : 'text-amber-700'}>当前链接无 token，订单查询受限</li>}
                   </ul>
                 </div>

src/components/PaymentForm.tsx

@@ -143,7 +143,7 @@ export default function PaymentForm({
           充值金额
         </label>
         <div className="grid grid-cols-3 gap-2">
-          {QUICK_AMOUNTS.map((val) => (
+          {QUICK_AMOUNTS.filter((val) => val <= maxAmount).map((val) => (
             <button
               key={val}
               type="button"
@@ -192,13 +192,19 @@ export default function PaymentForm({
         </div>
       </div>
 
-      {customAmount !== '' && !isValid && (
-        <div className={['text-xs', dark ? 'text-amber-300' : 'text-amber-700'].join(' ')}>
-          {
-            '\u91D1\u989D\u9700\u5728\u8303\u56F4\u5185\uFF0C\u4E14\u6700\u591A\u652F\u6301 2 \u4F4D\u5C0F\u6570\uFF08\u7CBE\u786E\u5230\u5206\uFF09'
-          }
-        </div>
-      )}
+      {customAmount !== '' && !isValid && (() => {
+        const num = parseFloat(customAmount);
+        let msg = '金额需在范围内，且最多支持 2 位小数（精确到分）';
+        if (!isNaN(num)) {
+          if (num < minAmount) msg = `单笔最低充值 ¥${minAmount}`;
+          else if (num > maxAmount) msg = `单笔最高充值 ¥${maxAmount}`;
+        }
+        return (
+          <div className={['text-xs', dark ? 'text-amber-300' : 'text-amber-700'].join(' ')}>
+            {msg}
+          </div>
+        );
+      })()}
 
       {/* Payment Type */}
       <div>

src/lib/config.ts

@@ -33,7 +33,9 @@ const envSchema = z.object({
 
   ORDER_TIMEOUT_MINUTES: z.string().default('5').transform(Number).pipe(z.number().int().positive()),
   MIN_RECHARGE_AMOUNT: z.string().default('1').transform(Number).pipe(z.number().positive()),
-  MAX_RECHARGE_AMOUNT: z.string().default('10000').transform(Number).pipe(z.number().positive()),
+  MAX_RECHARGE_AMOUNT: z.string().default('1000').transform(Number).pipe(z.number().positive()),
+  // 每日每用户最大累计充值额，0 = 不限制
+  MAX_DAILY_RECHARGE_AMOUNT: z.string().default('0').transform(Number).pipe(z.number().min(0)),
   PRODUCT_NAME: z.string().default('Sub2API Balance Recharge'),
 
   ADMIN_TOKEN: z.string().min(1),

src/lib/order/service.ts

@@ -44,6 +44,29 @@ export async function createOrder(input: CreateOrderInput): Promise<CreateOrderR
     throw new OrderError('TOO_MANY_PENDING', `Too many pending orders (${MAX_PENDING_ORDERS})`, 429);
   }
 
+  // 每日累计充值限额校验（0 = 不限制）
+  if (env.MAX_DAILY_RECHARGE_AMOUNT > 0) {
+    const todayStart = new Date();
+    todayStart.setUTCHours(0, 0, 0, 0);
+    const dailyAgg = await prisma.order.aggregate({
+      where: {
+        userId: input.userId,
+        status: { in: ['PAID', 'RECHARGING', 'COMPLETED'] },
+        paidAt: { gte: todayStart },
+      },
+      _sum: { amount: true },
+    });
+    const alreadyPaid = Number(dailyAgg._sum.amount ?? 0);
+    if (alreadyPaid + input.amount > env.MAX_DAILY_RECHARGE_AMOUNT) {
+      const remaining = Math.max(0, env.MAX_DAILY_RECHARGE_AMOUNT - alreadyPaid);
+      throw new OrderError(
+        'DAILY_LIMIT_EXCEEDED',
+        `今日累计充值已达上限，剩余可充值 ${remaining.toFixed(2)} 元`,
+        429,
+      );
+    }
+  }
+
   const expiresAt = new Date(Date.now() + env.ORDER_TIMEOUT_MINUTES * 60 * 1000);
   const order = await prisma.order.create({
     data: {