Phase 6 (Stufe 4): einmalige Config-Migration Mongo -> MySQL

- ConfigMigrator: kopiert Accounts, aktive Markets, Master-Trader,
  Copytrading-Settings (mit Fallback auf Alt-Felder im accounts-Dokument)
  und Demo-Positionen; Historie startet leer. Idempotent via Upserts.
- Getrennte Mini-Container fuer Quelle (Mongo) und Ziel (EF/MySQL),
  unabhaengig vom Provider-Toggle.
- Aufruf: PolyTrader.App --migrate-config (kein UI-Start).
- Erstlauf: 2344 Markets migriert; Accounts/Trader/Settings in lokaler
  Mongo leer (nichts zu migrieren).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Program.cs

@@ -4,6 +4,7 @@ using PolyTraderSharp.Extensions;
 using System.Net.Http;
 using System.Threading.Channels;
 using System.Windows.Forms;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Options;
@@ -23,8 +24,15 @@ internal static class Program
     public static IHost? AppHost { get; private set; }
 
 	[STAThread]
-	private static void Main()
+	private static void Main(string[] args)
 	{
+		// Einmalige Config-Migration Mongo -> MySQL (Phase 6, Stufe 4). Kein UI-Start.
+		if (args.Length > 0 && string.Equals(args[0], "--migrate-config", StringComparison.OrdinalIgnoreCase))
+		{
+			RunConfigMigration();
+			return;
+		}
+
 		ApplicationConfiguration.Initialize();
 
 			var modules = new System.Collections.Generic.List<IPolyTraderModule>
@@ -208,4 +216,26 @@ internal static class Program
 			Application.Run(launcher);
 			AppHost.StopAsync().GetAwaiter().GetResult();
 		}
+
+	private static void RunConfigMigration()
+	{
+		var config = new Microsoft.Extensions.Configuration.ConfigurationBuilder()
+			.SetBasePath(System.IO.Directory.GetCurrentDirectory())
+			.AddJsonFile("appsettings.json", optional: true)
+			.AddJsonFile("appsettings.Local.json", optional: true)
+			.AddEnvironmentVariables()
+			.Build();
+
+		var mongoConn = config["Database:ConnectionString"] ?? "mongodb://localhost:27017";
+		var mongoDbName = config["Database:DatabaseName"] ?? "PolyTraderDB";
+		var mySql = config["Database:MySqlConnectionString"] ?? string.Empty;
+
+		if (string.IsNullOrWhiteSpace(mySql))
+		{
+			Console.WriteLine("FEHLER: Database:MySqlConnectionString fehlt (appsettings.Local.json).");
+			return;
+		}
+
+		Services.ConfigMigrator.Run(mongoConn, mongoDbName, mySql);
+	}
 }