more export UI code

src/ExportOperation/Exporter.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Diagnostics.Contracts;
+using System.IO;
+using MercuryConverter.Data;
+using MercuryConverter.UI.Views;
+
+namespace MercuryConverter.ExportOperation;
+
+public class ExportResult
+{
+    public enum Status
+    {
+        Successful, Failed, WithWarnings
+    }
+    public required Status status;
+    /// <summary>
+    /// Populated when status is Failed or WithWarnings.
+    /// </summary>
+    public string? message;
+}
+
+public class Exporter
+{
+    public static ExportResult Run(string outputPath, Song song)
+    {
+        var exportPath = Path.Combine(outputPath, song.FolderName);
+        Console.WriteLine($"Exporting to {exportPath}...");
+        return new ExportResult { status = ExportResult.Status.Failed, message = "Unimplemented" };
+    }
+}