chore: establish V1.1 recovery baseline

miniapp/pages/checkin/checkin.wxml

@@ -0,0 +1,41 @@
+<!-- 签到码页 U31 -->
+<view class="page">
+  <view class="header">
+    <text class="title">活动签到</text>
+  </view>
+
+  <view wx:if="{{loading}}" class="loading-state">
+    <text>生成签到码中...</text>
+  </view>
+
+  <view wx:if="{{error}}" class="error-state">
+    <text>{{error}}</text>
+    <button class="btn-refresh" bindtap="onRefresh">重试</button>
+  </view>
+
+  <view wx:if="{{!loading && !error}}" class="checkin-card">
+    <view class="activity-info">
+      <text class="activity-title">{{activityTitle}}</text>
+      <text class="activity-location">📍 {{locationName}}</text>
+    </view>
+
+    <view class="qr-section">
+      <view class="qr-placeholder">
+        <text class="qr-icon">▣</text>
+      </view>
+      <text class="qr-hint">请向工作人员展示此签到码</text>
+    </view>
+
+    <view class="token-section">
+      <text class="token-label">签到码</text>
+      <text class="token-value" selectable="true">{{token}}</text>
+      <button class="btn-copy" bindtap="copyToken">复制签到码</button>
+    </view>
+
+    <view class="expire-info">
+      <text>有效期：{{formatExpiresAt(expiresAt)}}</text>
+    </view>
+  </view>
+
+  <button class="btn-refresh-page" bindtap="onRefresh">刷新签到码</button>
+</view>