SIGNAL/SLOT migration: socket_handler (5), targettimer (1), socketreader (2) + status update

- Migrated old SIGNAL/SLOT connect syntax to function-pointer syntax
- socket_handler.cpp: timeout, connected, disconnected, readyRead, bytesWritten
- targettimer.cpp: timeout → MyTimerSlot
- socketreader.cpp: readyRead, error (with QOverload for overloaded signal)
- Updated MIGRATION_STATUS.md with migration progress
- Part of Qt5→Qt6 migration with C++17 constraint (RTI 7.7.0 compatibility)

qt6-after/qt6-migrated-legatus/Lts/Services/NmeaManagement/socket_handler.cpp

@@ -28,8 +28,8 @@ SocketHandler::SocketHandler(const std::shared_ptr<DdsHandler> &ddsHandler,
   m_reconnectTimer = new QTimer(this);
 
   // setup signal and slot
-  connect(m_reconnectTimer, SIGNAL(timeout()),
-          this, SLOT(reconnectTimerSlot()));
+  connect(m_reconnectTimer, &QTimer::timeout,
+          this, &SocketHandler::reconnectTimerSlot);
 
 }
 
@@ -38,11 +38,11 @@ void SocketHandler::init(QString nmeaHost, int nmeaPort)
   m_nmeaHost = nmeaHost;
   m_nmeaPort = nmeaPort;
   socket = new QUdpSocket(this);
-  connect(socket, SIGNAL(connected()), this, SLOT(connected()));
-  connect(socket, SIGNAL(disconnected()), this, SLOT(disconnected()));
-  connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
+  connect(socket, &QUdpSocket::connected, this, &SocketHandler::connected);
+  connect(socket, &QUdpSocket::disconnected, this, &SocketHandler::disconnected);
+  connect(socket, &QUdpSocket::readyRead, this, &SocketHandler::readyRead);
 
-  connect(socket, SIGNAL(bytesWritten(qint64)), this, SLOT(bytesWritten(qint64)));
+  connect(socket, &QUdpSocket::bytesWritten, this, &SocketHandler::bytesWritten);
 
   INFO_LOG(m_logger) << "Connecting,..";
   INFO_LOG(m_logger) << nmeaHost << " port: " << nmeaPort;