feat: remove empty directories

DownloadTask.cs

@@ -778,6 +778,9 @@ private void RemoveOldFiles(IDownloadTask_GetVersion info) {
             done += 1;
             this.SetStateData(done, total);
         }
+
+        // remove any empty directories
+        DirectoryHelper.RemoveEmptyDirectories(filesPath);
     }
 
     private async Task DownloadFile(Uri baseUri, string filesPath, string[] outputPaths, string hash) {

Util/DirectoryHelper.cs

@@ -0,0 +1,12 @@
+namespace Heliosphere.Util;
+
+internal static class DirectoryHelper {
+    internal static void RemoveEmptyDirectories(string root) {
+        foreach (var path in Directory.GetDirectories(root)) {
+            RemoveEmptyDirectories(path);
+            if (!Directory.EnumerateFileSystemEntries(path).Any()) {
+                Directory.Delete(path, false);
+            }
+        }
+    }
+}