feat: implement MVP Phase 1 — full-area scan with ADC data collection

- Send scan command: all 5 regions LED on, brightness 128
- Listen for ADC notify (17 bytes) instead of broken queryStatus
- Parse and display PD1-PD7 values with visual bars
- Show VBAT/battery info
- Store scan PD data in globalData for Phase 3 smart adjustment
- 8s timeout fallback, stop LED on page unload

miniprogram/pages/auto-scan/auto-scan.wxml

@@ -1,30 +1,39 @@
 <view class="page">
   <view class="page-header page-header-pink" style="padding-top: {{statusBarHeight + 24}}px;">
     <view class="nav-back" bindtap="onBack">‹ 返回</view>
-    <view class="page-header-title">自动扫描</view>
-    <view class="page-header-subtitle">正在识别区域...</view>
+    <view class="page-header-title">区域扫描</view>
+    <view class="page-header-subtitle">{{scanning ? '正在采集数据...' : '扫描完成'}}</view>
   </view>
 
   <view class="page-content">
-    <view class="page-title">自动扫描区域</view>
-
-    <view class="scan-container">
+    <view class="scan-container" wx:if="{{scanning}}">
       <view class="face-outline">
         <view class="scan-line"></view>
       </view>
+      <view class="scan-progress-bar">
+        <view class="scan-progress-fill" style="width: {{scanProgress}}%"></view>
+      </view>
+      <view class="scan-status">全域LED已开启，亮度 128，等待PD数据回传...</view>
     </view>
 
-    <view class="scan-hint">请正确佩戴设备</view>
-    <view class="scan-hint" style="font-size:24rpx;color:#999;margin-top:8rpx;">连接设备后可获取检测数据</view>
-
-    <view class="scan-progress" wx:if="{{scanning}}">
-      正在扫描... <text class="highlight">{{regionData.length || 3}}</text> 个区域
+    <view class="scan-result" wx:if="{{!scanning && pdValues.length > 0}}">
+      <view class="result-title">PD 采集结果</view>
+      <view class="pd-list">
+        <view class="pd-item" wx:for="{{pdValues}}" wx:key="region">
+          <view class="pd-region">{{item.region}}</view>
+          <view class="pd-value {{item.pd > 0 ? '' : 'pd-empty'}}">{{item.pdText}}</view>
+          <view class="pd-bar-bg" wx:if="{{item.pd > 0}}">
+            <view class="pd-bar-fill" style="width: {{item.pd > 4095 ? 100 : item.pd / 40.95}}%"></view>
+          </view>
+        </view>
+      </view>
+      <view class="vbat-info" wx:if="{{vbat > 0}}">
+        电池电压: {{vbat}}mV ({{battery}}%)
+      </view>
     </view>
 
-    <view class="detected-tags" wx:if="{{regionData.length > 0}}">
-      <text class="detected-tag" wx:for="{{regionData}}" wx:key="region">{{item.region}}</text>
-    </view>
+    <view class="scan-error" wx:if="{{error}}">{{error}}</view>
 
-    <button class="btn-primary mt-30" wx:if="{{!scanning}}" bindtap="onNext">设置参数</button>
+    <button class="btn-primary mt-30" wx:if="{{!scanning}}" bindtap="onNext">下一步</button>
   </view>
 </view>