Fix Language Change And Name Collision In Presets

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Core/PresetManager.cs

@@ -116,7 +116,11 @@ public static class PresetManager
         return Path.Combine(root, "UserData", "ADOFAIRenderer", "Presets");
     }
 
-    private static string GetSafeFileName(string name)
+    /// <summary>
+    /// File name (without extension) of the preset file for the given preset name: every character that is invalid
+    /// in a file name is replaced with '_'. Different preset names can map to the same file name (e.g. "a/b" and "a_b").
+    /// </summary>
+    internal static string GetSafeFileName(string name)
     {
         return Path.GetInvalidFileNameChars().Aggregate(name, (current, c) => current.Replace(c, '_'));
     }