Android delegated proving times out when the transaction pane is hidden

From feedback ticket #139 (https://app.notion.com/3ae99411cf9081888cc0f331767dc167). Reported on Android.

## Symptom

Hiding the transaction pane or switching to another app caused repeated remote-prover timeouts. The retries later succeeded. When the pane remained visible, proving was reliable.

## Expected

Delegated proving and transaction tracking should continue when the app is backgrounded or the progress pane is hidden. UI lifecycle changes should not cancel, suspend, or starve the request.

## Investigation needed

Compare foreground and background behavior for the native bridge, WebView lifecycle, network access, timers, and transaction queue. Confirm whether the timeout occurs at the remote prover or because the app stops processing its response.

## Related

#419 handles general remote-prover unavailability and fallback. This issue is the Android lifecycle-dependent timeout trigger.

Feedback DB ref: ticket 139.

调查Android代码库中的原生桥接和WebView生命周期处理。查找应用进入后台时的事务队列管理和网络请求处理。比较前台和后台状态之间的日志或行为，以确定超时的来源。确认问题是在请求取消、响应处理还是计时器饥饿中。

由索引模型根据 Issue 内容生成。