chore: remove all mock/debug code for production release

Miniprogram:
- ENV switched to 'prod' (disables __DEV__ flag)
- Deleted mock.js and test-ble-frame.js
- Removed mockBind/mockPurchase from api.js
- Removed all debug UI panels and onMock* handlers from 6 pages
- Removed mock purchase fallback in subscribe-plans
- Removed SIMPLE PERIPHERAL dev board from BLE scan

Server:
- Removed /device/mock-bind route
- Removed /subscription/mock-purchase route
- Removed dev_openid fallback in wechat.js
- Removed mockBind() from binding.dao.js
- Removed mock fallback in purchase endpoint
- NODE_ENV default changed to 'production'

Admin:
- ENV switched to 'prod'

All mock code preserved in 'test' branch for future development use.

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

@@ -17,11 +17,6 @@
     <view class="scan-hint">请将面罩对准面部</view>
     <view class="scan-hint" style="font-size:24rpx;color:#999;margin-top:8rpx;">连接设备后可获取皮肤数据</view>
 
-    <view class="debug-actions" wx:if="{{devMode}}">
-      <view class="debug-label">🔧 调试工具</view>
-      <button class="btn-secondary btn-sm" bindtap="onMockScanDone">模拟扫描完成</button>
-    </view>
-
     <view class="scan-progress" wx:if="{{scanning}}">
       正在扫描... <text class="highlight">{{regionData.length || 3}}</text> 个区域
     </view>