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/Proxies/HighLevelArchitecture/Apache/socketreader.cpp

@@ -24,8 +24,9 @@ bool SocketReader::init(const QString &host, quint16 port, int hlaRequestIdentif
   DEBUG_LOG(m_logger) << "SR " << hlaRequestIdentifier << ": Trying to establish connection to " << host << ":" << port;
 
   m_hlaRequestIdentifier = hlaRequestIdentifier;
-  connect(m_socket, SIGNAL(readyRead()), this, SLOT(onReadyRead()));
-  connect(m_socket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(onSocketError(QAbstractSocket::SocketError)));
+  connect(m_socket, &QTcpSocket::readyRead, this, &SocketReader::onReadyRead);
+  connect(m_socket, QOverload<QAbstractSocket::SocketError>::of(&QTcpSocket::error),
+          this, &SocketReader::onSocketError);
 
   m_socket->connectToHost(host, port, QIODevice::ReadOnly);
   return m_socket->waitForConnected(1000);