[AI Generated]: feat(*): 新增 autoConnect 自动重连机制、OTA 断连兜底触发，修复 diff 为零时颜色与箭头展示异常

miniprogram/pages/home/home.less

@@ -254,6 +254,10 @@
 						.diff-up {
 							color: #FF4D4F;
 						}
+
+						.diff-neutral {
+							color: #000000;
+						}
 					}
 
 					.diff-label {

miniprogram/pages/home/home.ts

@@ -83,10 +83,19 @@ Page({
 
     onShow() {
         // 每次进入 tab 同步最新设备状态
+        const connected = lefuService.isConnected
         this.setData({
-            'device.connected': lefuService.isConnected,
+            'device.connected': connected,
             'device.name': lefuService.deviceInfo?.modelNumber ?? '智能体重秤',
         })
+        // 进来时设备已连接（如热启动/切 tab 回来），onDeviceConnect 不会再触发，需在此补一次检测
+        if (connected && !this._otaChecked) {
+            this._checkOta()
+        }
+        // 断连时自动扫描重连，重连成功后 onDeviceConnect 回调会触发 OTA 检测
+        if (!connected) {
+            lefuService.autoConnect()
+        }
         this.loadData()
     },
 

miniprogram/pages/home/home.wxml

@@ -48,13 +48,13 @@
                         </view>
                         <view class="weight-diff">
                             <view class="diff-num-wrap">
-                                <view class="diff-num {{ record.diff < 0 ? 'diff-down' : 'diff-up' }}">{{ record.diff < 0 ? -record.diff : record.diff }}</view>
+                                <view class="diff-num {{ record.diff < 0 ? 'diff-down' : (record.diff > 0 ? 'diff-up' : 'diff-neutral') }}">{{ record.diff < 0 ? -record.diff : record.diff }}</view>
                                 <view class="diff-unit">
                                     kg
-                                    <text class="diff-arrow {{ record.diff < 0 ? 'arrow-down' : 'arrow-up' }}"></text>
+                                    <text wx:if="{{ record.diff !== 0 }}" class="diff-arrow {{ record.diff < 0 ? 'arrow-down' : 'arrow-up' }}"></text>
                                 </view>
                             </view>
-                            <view class="diff-label">{{ record.diff < 0 ? '体重较上次减轻' : '体重较上次增加' }}</view>
+                            <view class="diff-label">{{ record.diff < 0 ? '体重较上次减轻' : (record.diff > 0 ? '体重较上次增加' : '与上次持平') }}</view>
                         </view>
                     </view>