[Bug]: "Open Project" dialog doesn't show dot directories

### What happened?

On Linux (Ubuntu), the File / Open Project dialog doesn't list directory name starting with a dot.
Specifically, it doesn't list `~/.local`, which is where Rivet installs the example plugin.

### What was the expected functionality?

All folders are listed.

### Describe your environment

Ubuntu 22.04.2 LTS on Windows Subsystem for Linux (WSL)

### Relevant log output

_No response_

### Relevant screenshots

_No response_

### Code of Conduct

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

Start by locating the File / Open Project dialog and reproduce the directory listing on Ubuntu or WSL. Trace how directory names are filtered, then verify that hidden folders such as ~/.local appear alongside other folders.

Written by the indexing model from the issue text.