Executables can't be found if spotlight is disabled

My application uses this module, and it doesn't work for one user (see https://github.com/httptoolkit/feedback/issues/21), because they've disabled spotlight, so `mdfind` searches return:

```
mdfind[30268:56473] Metadata.framework [Error]: couldn't get the client port
```

I think you could work around this, by falling back to searching the Applications folder manually instead (potentially printing a warning so users know why it might be slow). What do you think?

Thanks for the module btw, it's been really useful!

Start by inspecting the module's executable lookup entry point and reproducing the failing mdfind behavior when Spotlight is disabled. Check how applications are located, then verify that the fallback can find an executable in the Applications folder and that any warning is appropriate.

Written by the indexing model from the issue text.