Android Import or export categories doesn't work

- **OS name and version**: Android 13
- **ActivityWatch version**:  v0.12.1 (rust)

## Describe the bug
Can't import and export categories (whebln clicked doesn't work), and when click export, the application crashes

## To Reproduce
Steps to reproduce the behavior:
1. Go to settings
3. Scroll down to Categorization
4. Click on import or export

## Expected behavior
Open the folder explorer to import or export a file.

## Documentation


## Additional context

Samsung One UI v5.1
With dark theme
And The application was in the dark theme