Insufficient contrast on shaded (currently playing) episode in list

### Checklist

- [x] I have used the search function for [**OPEN**](https://github.com/AntennaPod/AntennaPod/issues) issues to see if someone else has already submitted the same bug report.
- [x] I have **also** used the search function for [**CLOSED**](https://github.com/AntennaPod/AntennaPod/issues?q=is%3Aissue+is%3Aclosed) issues to see if the problem is already solved and just waiting to be released.
- [x] I will describe the problem with as much detail as possible.
- [x] If the bug only to occurs with a certain podcast, I will include the URL of that podcast.

### App version

3.12.0-beta1

### Android version

16

### Device model

_No response_

### First occurred

_No response_

### Steps to reproduce

Play an episode from the queue

### Expected behaviour

The currently playing episode is highlighted in the list, and all its details remain legible.

### Current behaviour

The currently playing episode is highlighted in the list, but the insufficient contrast makes it difficult to read details, both when using light and dark theme. (On the other hand, multi-selected episodes do not display this issue.)

Small related comment: it would also look tidier if the shading and the scrollbar did not overlap.

### Crash logs

_No response_