feat: 移动端新增客户页面添加客户编码字段

- 新增客户编码输入框（customerCode）
- 位于客户名称字段之前

fund-mobile/src/views/customer/Add.vue

@@ -4,6 +4,13 @@
     
     <van-form @submit="onSubmit">
       <van-cell-group inset>
+        <van-field
+          v-model="form.customerCode"
+          name="customerCode"
+          label="客户编码"
+          placeholder="请输入客户编码"
+        />
+        
         <van-field
           v-model="form.customerName"
           name="customerName"
@@ -100,6 +107,7 @@ const submitting = ref(false)
 const showLevelPicker = ref(false)
 
 const form = ref({
+  customerCode: '',
   customerName: '',
   customerShort: '',
   phone: '',
@@ -136,6 +144,7 @@ const onSubmit = async () => {
   submitting.value = true
   try {
     await createCustomer({
+      customerCode: form.value.customerCode,
       customerName: form.value.customerName,
       customerShort: form.value.customerShort,
       phone: form.value.phone,