chore: import Musify.Worker into monorepo (preserving history)

git-subtree-dir: Musify.Worker
git-subtree-mainline: c3cdd3bc0f
git-subtree-split: 868860fff9

Musify.Worker/Worker/Worker.cs

@@ -0,0 +1,9 @@
+namespace Musify.Worker
+{
+    public class Worker : BackgroundService
+    {
+        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+        {
+        }
+    }
+}