refactor(arrivalRegister): 统一变量声明方式，提升代码一致性

- 将多个方法中的变量声明从const改为var，确保一致性
- 优化了代码格式，提升可读性
- 继续改善到货登记逻辑，增强用户体验

pages/arrivalRegister/index.vue

@@ -763,7 +763,7 @@
              * @param {Object} target
              */
             findIndex(arr, target) {
-                const result = [];
+                var result = [];
                 arr.map((item, index) => {
                     if (item === target) {
                         result.push(index);
@@ -814,7 +814,7 @@
                     }
                 } else {
                     // 清除搜索条件
-                    const fields = ['mobile_register_all_search', 'stock_in_with_stock_in_items_inhouse', 'tracking_no', 'box_sn'];
+                    var fields = ['mobile_register_all_search', 'stock_in_with_stock_in_items_inhouse', 'tracking_no', 'box_sn'];
                     this.searchParams[fields[this.index]] = '';
                     this.input_flag = false;
                     this.clearInputAndFocus(); //再次获取焦点
@@ -1013,7 +1013,7 @@
              * 修改自营数据提交
              */
             saveZyGoodsDataSubmit() {
-                const isEmptyMpq = this.saveZyGoodsParams.every(obj => {
+                var isEmptyMpq = this.saveZyGoodsParams.every(obj => {
                     return obj.hasOwnProperty('mpq') && obj.mpq !== '';
                 });
 
@@ -1026,7 +1026,7 @@
                     return false
                 }
 
-                const hasError = this.saveZyGoodsParams.filter(item => item.packing === 5).some(({ standard_length, unit_length }, index) => {
+                var hasError = this.saveZyGoodsParams.filter(item => item.packing === 5).some(({ standard_length, unit_length }, index) => {
                     if (this.standardSizeIndex == 0 && !standard_length) {
                         uni.showModal({
                             title: '提示',
@@ -1151,7 +1151,7 @@
                     stock_in_id[0] = id;
                 }
 
-                const allElementsEqual = this.filter_id_warehouse_id.every(element => element === this.filter_id_warehouse_id[0]);
+                var allElementsEqual = this.filter_id_warehouse_id.every(element => element === this.filter_id_warehouse_id[0]);
                 if (!allElementsEqual) {
                     uni.showModal({
                         title: '提示',
@@ -1217,7 +1217,7 @@
                     });
                     return false;
                 }
-                const allElementsEqual = this.filter_id_warehouse_id.every(element => element === this.filter_id_warehouse_id[0]);
+                var allElementsEqual = this.filter_id_warehouse_id.every(element => element === this.filter_id_warehouse_id[0]);
                 if (!allElementsEqual) {
                     uni.showModal({
                         title: '提示',