lsws does not create the virtual host root directory when adding a virtual host


Hi,
After working for a long time to fix the 404 error, I finally solved the problem by creating the root directory of the virtual host.

```
sudo mkdir /usr/local/lsws/test
```

I think like the config file, lsws should show error if this directory doesn't exist.

Reproduce virtual-host creation with a root directory such as /usr/local/lsws/test absent, then trace the virtual-host configuration and validation path. Done means adding a virtual host with a missing root directory produces a clear error instead of leading to a 404; no specific files or tests are named in the issue.

Written by the indexing model from the issue text.