feat: 实现站内USDT收银台支付流程

- 后端: payment.go 支付处理(创建订单/回调通知/状态查询/签名算法)
- 后端: 新增公开支付通道API(PublicList,不暴露config)
- 前端: Checkout.vue 收银台页面(倒计时/二维码/支付轮询)
- 前端: Cart.vue 对接动态支付通道,选择bepusdt跳转收银台
- 前端: API添加paymentChannelApi和orderApi支付方法
- 路由: 注册checkout路由和支付相关API

frontend/src/views/user/Cart.vue

@@ -226,7 +226,7 @@ import {
   Wallet, Coin, ChatDotRound
 } from '@element-plus/icons-vue'
 import { useCartStore } from '../../store/cart'
-import { systemApi, addressApi, orderApi } from '../../api'
+import { systemApi, addressApi, orderApi, paymentChannelApi } from '../../api'
 import { getFirstImage } from '../../utils/image'
 import BackNav from '../../components/BackNav.vue'
 
@@ -252,21 +252,23 @@ const addressForm = reactive({
   is_default: false
 })
 
-const allPaymentMethods = [
-  { value: 'balance', label: '余额支付', icon: markRaw(Wallet) },
-  { value: 'alipay', label: '支付宝', icon: markRaw(Coin) },
-  { value: 'wechat', label: '微信支付', icon: markRaw(ChatDotRound) },
-]
+const typeIconMap: Record<string, any> = {
+  balance: markRaw(Wallet),
+  alipay: markRaw(Coin),
+  wechat: markRaw(ChatDotRound),
+  bepusdt: markRaw(Coin),
+  bank: markRaw(CreditCard),
+  other: markRaw(Coin),
+}
+
+const paymentChannels = ref<any[]>([])
 
 const availablePayments = computed(() => {
-  const enabledStr = settings.value.enabled_payments
-  if (!enabledStr) return [allPaymentMethods[0]]
-  try {
-    const enabled = JSON.parse(enabledStr)
-    return allPaymentMethods.filter(m => enabled.includes(m.value))
-  } catch {
-    return [allPaymentMethods[0]]
-  }
+  return paymentChannels.value.map(ch => ({
+    value: ch.code,
+    label: ch.name,
+    icon: typeIconMap[ch.type] || markRaw(Coin),
+  }))
 })
 
 const selectAll = computed({
@@ -321,8 +323,15 @@ async function fetchSettings() {
   try {
     const res: any = await systemApi.getPublicSettings()
     settings.value = res.data || {}
-    if (availablePayments.value.length > 0 && !selectedPayment.value) {
-      selectedPayment.value = availablePayments.value[0].value
+  } catch {}
+}
+
+async function fetchPaymentChannels() {
+  try {
+    const res: any = await paymentChannelApi.list()
+    paymentChannels.value = res.data || []
+    if (paymentChannels.value.length > 0 && !selectedPayment.value) {
+      selectedPayment.value = paymentChannels.value[0].code
     }
   } catch {}
 }
@@ -416,14 +425,20 @@ async function handleCheckout() {
   
   submitting.value = true
   try {
-    await orderApi.create({ 
+    const res: any = await orderApi.create({ 
       shipping_address_id: selectedAddressId.value,
       payment_method: selectedPayment.value,
       cart_item_ids: selectedIds.value
     })
     ElMessage.success('订单创建成功')
     await cartStore.fetchCart()
-    router.push('/orders')
+    const orderId = res.data?.id
+    const selectedChannel = paymentChannels.value.find(ch => ch.code === selectedPayment.value)
+    if (selectedChannel?.type === 'bepusdt' && orderId) {
+      router.push(`/checkout/${orderId}`)
+    } else {
+      router.push('/orders')
+    }
   } catch (err: any) {
     ElMessage.error(err.response?.data?.error || '订单创建失败')
   } finally {
@@ -441,6 +456,7 @@ onMounted(() => {
   cartStore.fetchCart()
   fetchSettings()
   fetchAddresses()
+  fetchPaymentChannels()
 })
 </script>