Phase 6 (Stufe 5): Default-Provider auf MySQL + Readback-Verifikation

- appsettings.json: Database:Provider = "MySql" (voller Umstieg).
- ConfigMigrator.VerifyMySql + CLI --verify-mysql: liest Accounts,
  Settings, Trader, Markets aus MySQL zurueck.
- Verifiziert: 3 Accounts, 3 Settings, 32 Trader (23 aktiv),
  2344 Markets; Werte/AssignedAccountIds stimmen mit Exporten ueberein.

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

Program.cs

@@ -41,6 +41,13 @@ internal static class Program
 			return;
 		}
 
+		// Readback-Verifikation der migrierten Config aus MySQL. Kein UI-Start.
+		if (args.Length > 0 && string.Equals(args[0], "--verify-mysql", StringComparison.OrdinalIgnoreCase))
+		{
+			RunVerifyMySql();
+			return;
+		}
+
 		ApplicationConfiguration.Initialize();
 
 			var modules = new System.Collections.Generic.List<IPolyTraderModule>
@@ -268,4 +275,23 @@ internal static class Program
 
 		Services.ConfigMigrator.RunFromJson(folder, mySql);
 	}
+
+	private static void RunVerifyMySql()
+	{
+		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 mySql = config["Database:MySqlConnectionString"] ?? string.Empty;
+		if (string.IsNullOrWhiteSpace(mySql))
+		{
+			Console.WriteLine("FEHLER: Database:MySqlConnectionString fehlt (appsettings.Local.json).");
+			return;
+		}
+
+		Services.ConfigMigrator.VerifyMySql(mySql);
+	}
 }