Maui FilePicker results in This platform does not support this file type.

### Description

I am building a desktop app in .NET Maui which targets Windows and MacOS. When using the built-in FilePicker on Mac (Catalyst) I get the following error:

{System.PlatformNotSupportedException: This platform does not support this file type. at Microsoft.Maui.Storage.FilePickerFileType.GetPlatformFileType(DevicePlatform platform) at Microsoft.Maui.Storage.FilePickerFileType.get_Value() at Microsoft.Maui.S…}

I have tried multiple file types, including csv, jpg, text/csv but nothing works.

`public async Task ImportCSV()
{
try
{
var customFileType = new FilePickerFileType(
new Dictionary>
{
{ DevicePlatform.WinUI, new[] { ".csv" } },
{ DevicePlatform.macOS, new[] {"csv"} }
});

PickOptions options = new()
{
PickerTitle = "Please select a csv file",
FileTypes = customFileType
};

var file = await FilePicker.Default.PickAsync(options);

if (file != null)
{
string filePath = AppStateService.fixMacFilePath(file.FullPath);

AppStateService.AppState.csvFilePath = filePath;

await InitiateCsvMapping();
}
}
catch (Exception ex)
{

}
}`

### Steps to Reproduce

1. Create a new Maui app.
2. Remove iOS and Android targets from project file.
3. Execute the shared code

### Version with bug

6.0.400

### Last version that worked well

Unknown/Other

### Affected platforms

macOS

### Affected platform versions

MacCatalyst 14.0

### Did you find any workaround?

The documentation does say that I should "Enable iCloud capabilities" but does not provide any links or other information regarding this. I did some digging, and found some documentation that says that it necessary to do this via the Entitlements.plist file which I did but it seems to only be relevant when publishing your app to the App store which I am not during development. I don't even care about iCloud right now. I just want to select a CSV file from my own desktop.

### Relevant log output

```shell
{System.PlatformNotSupportedException: This platform does not support this file type.
at Microsoft.Maui.Storage.FilePickerFileType.GetPlatformFileType(DevicePlatform platform)
at Microsoft.Maui.Storage.FilePickerFileType.get_Value()
at Microsoft.Maui.S…}
```

Reproduce the shared FilePicker code from the issue in a .NET MAUI app targeting MacCatalyst 14.0, then trace Microsoft.Maui.Storage.FilePickerFileType.GetPlatformFileType and its platform-specific handling. Check the referenced Entitlements.plist guidance and existing FilePicker tests or implementation paths. Done means selecting a CSV or other listed file type on macOS no longer raises PlatformNotSupportedException.

Written by the indexing model from the issue text.