fix: 扫码出库类型改为必选，移除默认值SALES

- outbound_type 默认值: SALES → '' (空)
- el-select 新增 clearable
- rules 新增 outbound_type required 校验

inventory-web/src/views/outbound/create.vue

@@ -166,7 +166,7 @@
           <el-row :gutter="15">
             <el-col :span="24" :md="8">
               <el-form-item label="出库类型" prop="outbound_type">
-                <el-select v-model="form.outbound_type" placeholder="请选择类型" style="width: 100%">
+                <el-select v-model="form.outbound_type" placeholder="请选择类型" style="width: 100%" clearable>
                   <el-option label="销售出库" value="SALES" />
                   <el-option label="内部领用" value="USE" />
                   <el-option label="生产出库" value="PRODUCTION" />
@@ -323,13 +323,14 @@ const lastY = ref(0)
 const operatorOptions = ref<string[]>([])
 
 const form = reactive({
-  outbound_type: 'SALES',
+  outbound_type: '',
   consumer_name: '',
   operator_name: '',
   remark: ''
 })
 
 const rules = {
+  outbound_type: [{ required: true, message: '请选择出库类型', trigger: 'change' }],
   consumer_name: [{ required: true, message: '请输入领用人姓名', trigger: 'blur' }],
   operator_name: [{ required: true, message: '请指定操作员', trigger: 'change' }]
 }