fix(支付): 根据企业登录状态自动选择支付方式

当用户是企业登录时，默认选择余额支付，否则选择微信支付。同时修复企业登录状态下余额支付选项的显示问题。

src/pages/product/components/checkout.vue

@@ -22,7 +22,15 @@ const { tel, userid: ab98Userid, name } = storeToRefs(ab98UserStore)
 const selectedPayment = ref<'wechat' | 'balance'>('wechat')
 const contact = ref("")
 const remark = ref("")
-const submitting = ref(false)
+const submitting = ref(false);
+
+watch(corpidLogin, (newValue) => {
+  if (newValue) {
+    selectedPayment.value = 'balance';
+  } else {
+    selectedPayment.value = 'wechat';
+  }
+}, { immediate: true });
 
 function callWxJsApi(paymentInfo: WxJsApiPreCreateResponse) {
   return new Promise((resolve, reject) => {
@@ -194,7 +202,7 @@ async function handleSubmit() {
           <van-icon v-if="selectedPayment === 'wechat'" name="success" class="check-icon" />
         </van-cell>
 
-        <van-cell
+        <van-cell v-if="corpidLogin"
           :class="['payment-option', { selected: selectedPayment === 'balance', disabled: balance < totalPrice }]"
           @click="selectedPayment = 'balance'">
           <van-icon name="balance-o" class="method-icon" />