fix: auth status should error for unknown/unconfigured host

[q-soriarty]

Problem

`copia-cli auth status --host nonexistent.example.com` shows the default host's status instead of erroring.

Expected behavior

```
$ copia-cli auth status --host nonexistent.example.com
Error: not logged in to nonexistent.example.com
```

Discovered by

gh CLI behavior comparison test.

[github-actions]

Closed by #120 (merged into develop).