No feedback to user about running simulations or their ending

还没有人认领这个 Issue。

I've got a simulation running now. After I clicked "simulate", I think I did get a "running simulation" timer initially, but it seems to have gone now, so I'm back to the screen with the "simulate" button:


There's nothing here to tell me if the simulation has finished (I assume it didn't because the screen changes to the one with plots when that does), or if the simulation has failed. I *think* it's still running---app.log still hasn't got anything after this:

```
2023-07-13 16:38:20,175|root|DEBUG - ComponentSync disconnecting from simConfig.cvode_active
2023-07-13 16:44:14,958|root|INFO - Scheduling simulation on 1 cores with ...
2023-07-13 16:44:14,963|root|DEBUG - Running single core simulation
```

but there's no way to tell. As a user, I don't know what to do---should I wait more, should I click simulate again, should I start again from scratch?

该 issue 没有指明源文件或测试。追踪 simulate 操作、其运行中的计时器状态、到 plots 的转换以及 app.log 消息；当 UI 能清楚区分运行中、已完成和失败状态，并告知用户该做什么时，即完成。

由索引模型根据 Issue 内容生成。