feat(apply): add amount formatter for fee input field

- Change input type from "number" to "digit" for better mobile keyboard support
- Add formatAmount() method to validate and format currency input
- Restrict decimal places to maximum 2 digits for CNY amounts
- Remove non-numeric characters except decimal point during input
- Handle multiple decimal points by keeping only the first one
- Improve user experience with proper currency input validation

pages/apply/index.vue

@@ -19,7 +19,14 @@
             <view class="form-section">
                 <view class="section-header">费用明细</view>
                 <u-form-item label="申请免收金额" prop="apply_fee_amount" required borderBottom>
-                    <u--input v-model="form.apply_fee_amount" placeholder="请输入" border="none" inputAlign="right" type="number"></u--input>
+                    <u--input 
+                        v-model="form.apply_fee_amount" 
+                        placeholder="请输入" 
+                        border="none" 
+                        inputAlign="right" 
+                        type="digit" 
+                        :formatter="formatAmount"
+                    ></u--input>
                 </u-form-item>
                 <view class="currency-hint">
                     <text>CNY-人民币元</text>
@@ -104,6 +111,31 @@
             },
 
             /**
+             * 金额格式化函数，限制只能输入两位小数
+             * @param {string} value - 输入的金额值
+             * @return {string} 格式化后的值
+             */
+            formatAmount(value) {
+                if (!value) return '';
+                
+                // 移除所有非数字和小数点的字符
+                var cleanValue = value.replace(/[^\d.]/g, '');
+                
+                // 处理多个小数点的情况，只保留第一个
+                var parts = cleanValue.split('.');
+                if (parts.length > 2) {
+                    cleanValue = parts[0] + '.' + parts.slice(1).join('');
+                }
+                
+                // 限制小数点后最多两位
+                if (parts.length === 2 && parts[1].length > 2) {
+                    cleanValue = parts[0] + '.' + parts[1].substring(0, 2);
+                }
+                
+                return cleanValue;
+            },
+
+            /**
              * 订单号输入事件，防抖获取客户名称
              * @return {void}
              */