feat(configmanager): add dedicated SQL Server port control

Add SqlServerPort property to connection string editor for explicit port
configuration, replacing the need to embed port in server name (e.g.,
localhost,1434). The port control generates the comma-separated format in
the connection string but does not parse it back when loading existing
connection strings.

NEW/tests/JdeScoping.ConfigManager.Tests/ViewModels/Forms/ConnectionStringsFormViewModelTests.cs

@@ -75,10 +75,11 @@ public class ConnectionStringsFormViewModelTests
         // Act
         var sut = new ConnectionStringsFormViewModel(model, _secureStoreManager, () => { }, _dialogService, _connectionTestService);
 
-        // Assert
+        // Assert - port stays embedded in server name, not parsed into SqlServerPort
         sut.Connections.Count.ShouldBe(1);
         sut.Connections[0].Provider.ShouldBe(ConnectionProvider.SqlServer);
         sut.Connections[0].Server.ShouldBe("localhost,1434");
+        sut.Connections[0].SqlServerPort.ShouldBeNull();
         sut.Connections[0].Database.ShouldBe("ScopingTool");
         sut.Connections[0].UserId.ShouldBe("scopingapp");
         sut.Connections[0].Password.ShouldBe("pass");