`run-adapter-static` also creates dynamic directories names as static folders

https://github.com/Jack5079/marko-slug-bug

```

<a href="/path">path</a>

<h1>here be $</h1>
```

Results in

```
dist
├── $
│   └── index.html
├── 404
│   └── index.html
├── path
│   └── index.html
└── index.html
```

But it should be:

```
dist
├── 404
│   └── index.html
├── path
│   └── index.html
└── index.html
```