Unclear docs for Mac

### Checklist

- [x] I added a descriptive title
- [x] I searched open reports and couldn't find a duplicate

### What happened?

I'm confused by the description of file type association for Macs:

https://conda.github.io/menuinst/defining-shortcuts/#associate-your-shortcut-with-file-types-and-url-protocols

It says:

"On macOS, use CFBundleDocumentTypes. Requires no placeholder. The opened document will be automatically passed as a regular command-line argument. "

which sounds great. But I don't think it's working. My application does not seem to be receiving a command line argument when I double-click a file to open it. It just opens the app and that's it.

Then it talks about:

"On macOS, opened files are dispatched via system events...."

OK that is more complicated. So, do I need this `event_handler` stuff to be able to double-click a file and have it sent to the app? The example given [here](https://github.com/conda/menuinst/blob/f6e8d74643d98ddfaedf642971fe939dcf58cd58/tests/data/jsons/file_types.json) is confusing to me. Is there an example like the win and linux cases where it's a Python script receiving the file as a command line argument? Or is that not actually possible on Mac and I have to figure out the `event_handler` method? (an examples of doing that in Python?)

### Conda Info

```shell
na
```

### Conda Config

```shell
na
```

### Conda list

```shell
na
```

### Additional Context

_No response_

Start with the linked file-type association documentation and the tests/data/jsons/file_types.json example. Determine whether macOS file opening passes a command-line argument or requires event_handler handling, and document the supported approach with a Python example if applicable. Done means the macOS behavior and setup are unambiguous to users.

Written by the indexing model from the issue text.