The file /etc/passwd has generated a large number of sandbox UIDs

During local development, 1000 sandbox UIDs are generated every time the service is restarted. Additionally, it is unsafe to start the service as the root user

```bash
$ grep "sandbox10" /etc/passwd | wc -l
41000
```
```bash
$ grep "sandbox10000" /etc/passwd | wc -l
41
```
```bash
$ grep "sandbox10999" /etc/passwd | wc -l
41
```

No source file, test, or entry point is named. Start by locating the service startup path that creates sandbox UIDs and the handling of root execution, then reproduce the restart behavior locally. Done means restarts no longer create an unbounded number of entries in /etc/passwd and starting as root is handled safely.

Written by the indexing model from the issue text.