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/index/index.wxml

@@ -9,10 +9,6 @@
       <text class="empty-icon">📱</text>
       <view class="empty-text">还没有绑定设备</view>
       <button class="btn-primary mt-30" bindtap="onAddDevice">扫码添加设备</button>
-      <view class="debug-actions" wx:if="{{devMode}}">
-        <view class="debug-label">🔧 调试工具</view>
-        <button class="btn-secondary btn-sm" bindtap="onMockBind">模拟绑定设备</button>
-      </view>
     </view>
   </view>