- rework: Logging logic and file logging

Nebula.Launcher/Program.cs

@@ -1,13 +1,22 @@
-using Avalonia;
+using System;
+using System.Threading;
+using Avalonia;
 
 namespace Nebula.Launcher;
 
 public static class Program
 {
+    private static Mutex? _mutex;
+    public static bool IsNewInstance;
+    [STAThread]
     public static void Main(string[] args)
     {
+        _mutex = new Mutex(true, $"Global\\Nebula.Launcher", out IsNewInstance);
         BuildAvaloniaApp()
             .StartWithClassicDesktopLifetime(args);
+        
+        if (IsNewInstance)
+            _mutex.ReleaseMutex();
     }
 
     // Avalonia configuration, don't remove; also used by visual designer.
@@ -18,4 +27,5 @@ public static class Program
             .WithInterFont()
             .LogToTrace();
     }
-}
+}
+