[Bug]: buildkit ext4 files (initfs and rootfs) are bigger (1,1 TB) than my whole disk on apfs

### I have done the following

- [x] I have searched the existing issues
- [ ] If possible, I've reproduced the issue using the 'main' branch of this project

### Steps to reproduce

Download and Installing 0.3

### Current behavior

The buildkit ext4 files (initfs and rootfs, see screenshots) are bigger together (1,1 TB) than my whole filesystem(apfs):

I found it, since Time Machine was taking forever, a look in activity monitor of the backupd shows me that it was coping the init.ext4 file for ours. Then I looked how big the file was.

### Expected behavior

Reasonable files size of these files, that Time Machine can simply copy it in time.

### Environment

```markdown
- OS: Sequio 15.6
- Xcode: non
- Container: 0.3
- MacBook Pro M2
```

### Relevant log output

```shell
see screenshots; I forgot to make a screenshot of the open files of the backupd
```

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Start by reproducing the issue on macOS 15.6 with Container 0.3 on an M2 Mac, then inspect the generated init.ext4 and rootfs files referenced in the screenshots. Confirm their apparent and actual sizes and how they affect Time Machine; done means the files have reasonable sizes and can be backed up in a practical time.

Written by the indexing model from the issue text.