DataGrid column header style not congruent with .NET 9 / Win 11 styles

I have a simple window with a DataGrid inside.
The project is targeting .NET 9 and Win 11 theming is enabled by adding the resources in `App.xaml` file:

```







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Column headers are displayed without taking into account the Win 11 styling.

Current behavior:


Expected behavior (I got this by removing `dgx:DataGridFilter.IsAutoFilterEnabled="True"` from my DataGrid XAML):


Note that the headers are displayed but the lack of contrast make them almost unreadable.
I'm opening this issue, but I'm ready to forward it to WPF repo if this is not a DataGridExtension-related issue.

Reproduce the issue in a .NET 9 WPF window using the App.xaml Fluent resource dictionary and a DataGrid with dgx:DataGridFilter.IsAutoFilterEnabled="True". Compare the resulting headers with the appearance when that attribute is removed, then determine whether the styling conflict belongs to DataGridExtensions or WPF. Done means the headers have readable contrast while auto-filtering remains enabled.

Scritto dal modello di indicizzazione a partire dal testo della issue.