Create assets dir before extract

StabilityMatrix.Avalonia/Helpers/UnixPrerequisiteHelper.cs

@@ -57,6 +57,7 @@ public class UnixPrerequisiteHelper : IPrerequisiteHelper
         
         progress?.Report(new ProgressReport(0, message: "Unpacking resources", isIndeterminate: true));
 
+        Directory.CreateDirectory(AssetsDir);
         foreach (var (assetUri, extractTo) in assets)
         {
             await Assets.ExtractAsset(assetUri, extractTo);