Variable speed time saving is not calculated correctly

### Description

Profile stats are not calculated correctly. When listening to an episode and using effects and skip feature the displayed stats do not align with the experience.

### Step-by-step reproduction instructions

1. Start the app with a clean install.
2. Do not sign in, ensuring nothing gets synced.
3. Follow any podcast.
4. Play an episode of that podcast. Ensure the episode is not too short; something around 1 hour should be fine.
5. Change the playback effects to `x5` speed and enable `Mad Max` trimming.
6. Tap the skip-forward button a few times until you reach the middle of the episode.
7. Let the episode play for a couple of minutes, ensuring it doesn't reach the end.
8. Pause the playback.
9. Close the app.
10. Reopen the app.
11. Check the profile stats. The time saved will not make sense — for example, while an episode might have been played for up to 30 minutes, the saved time due to Variable Speed might show something like 1 hour. In this scenario, the saved time from Variable Speed should not exceed the played up to timestamp.

### Screenshots or screen recording

_No response_

### Did you search for existing bug reports?

- [x] I have searched for existing bug reports.

### Device, Operating system, and Pocket Casts app version

Google Pixel 6, Android 14, Pocket Casts 7.77

Reproduce the profile-stats scenario on Android 14 with x5 playback speed, Mad Max trimming, and skip-forward before closing and reopening the app. Trace how playback effects and the played-to timestamp contribute to Variable Speed time saved; done means the saved time does not exceed the played-to timestamp in the reported scenario.

Written by the indexing model from the issue text.