[Bug]: Error log message is misleading: `handler for snapshotGet threw error notFound: "image snapshot for ref"`

### 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

Run `container system logs`, and run any image that's not been unpacked yet.

### Current behavior

The logs will container something like.

```console
2025-09-03 17:06:04.702630+0800 0x3adf Error 0x0 1099 0 container-core-images: [com.apple.container:ImagesHelper] handler for snapshotGet threw error notFound: "image snapshot for docker.io/library/ubuntu:24.04 with platform linux/amd64"
```

That this is listed as an error is misleading. It just means the image hasn't been unpacked yet.

### Expected behavior

No error at this point. Arguably this message is simply noise in this context.

### Environment

```markdown
- OS: 26 beta
- Xcode: 26 beta
- Container: 0.4.1
```

### Relevant log output

```shell

```

### Code of Conduct

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

Start by reproducing the report with `container system logs` while running an image that has not been unpacked, and inspect the code path for the `snapshotGet` handler. Confirm why the expected missing image snapshot is logged as an error, then verify that the resulting logs no longer report this normal condition as an error.

Written by the indexing model from the issue text.