"Keep unlocked" advanced setting on Android app doesn't release Vault after files are closed

### Summary

In the Android version of Cryptomator, with the "keep unlocked" advanced setting enabled, even after files are no longer in use, the Vault will still not lock even after the set auto lock duration time has passed.

### Please agree to the following

- [x] I have searched [existing issues](https://github.com/cryptomator/cryptomator/issues?q=) for duplicates
- [x] I agree to follow this project's [Code of Conduct](https://github.com/cryptomator/cryptomator/blob/develop/.github/CODE_OF_CONDUCT.md)

### What software is involved?

- Operating System: Android 16 (OnePlus 15)
- Cryptomator: 2.0.0
- …

### Volume Type

None

### Steps to Reproduce

1. Enable "keep unlocked" in settings.
2. Set Auto Lock timer to any time so it's enabled.
3. Unlock Vault
4. Open file
5. Close out file/application (for example, closing VLC app for a media file)
6. Wait x minutes (auto lock timer)
7. Observe how Vault is still unlocked

### Expected Behavior

Vault should lock after x minutes once the file has been closed.

Side issue: Also, disabling the "keep unlocked" option should immediately start applying.

### Actual Behavior

Vault does not lock and stays unlocked indefinitely.

Side issue: Disabling the "keep unlocked" option does not make it go back to not having files prevent the auto locking until the app is manually force stopped (not swiped away, I mean go into Android settings page for the app and press the force stop button)

### Reproducibility

Always

### Relevant Log Output

```shell

```

### Anything else?

Notification shows file as open timer as not decreasing at all (even though Cryptomator/VLC/etc has been closed).