Fix LogViewTelegramEdit m_logger and Qt::TextDate for Qt6

- Add m_logger member variable to LogViewTelegramEdit.hpp
- Initialize m_logger in LogViewTelegramEdit constructor
- Replace Qt::SystemLocaleLongDate with Qt::TextDate for Qt6 compatibility

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/TetraIF/LogView/LogViewTelegram.cpp

@@ -1630,7 +1630,7 @@ void LogViewTelegram::showMessageBox(const QString& a_errorText, const QString&
         QLatin1String("gesendete") : QLatin1String("gelesene"));
   QMessageBox::warning(QApplication::topLevelWidgets()[0], a_title,
       QString::fromUtf8("Das %5 Telegramm mit Protokoll %6 von %1 (Unix-Zeit: %2) und Länge %3 ist fehlerhaft:<br><br><b>%4</b>")
-      .arg(dt.toString(Qt::SystemLocaleLongDate)).arg(logTimeSec).arg(m_data.size()).arg(a_errorText, destStr).arg(m_Protocol));
+      .arg(dt.toString(Qt::TextDate)).arg(logTimeSec).arg(m_data.size()).arg(a_errorText, destStr).arg(m_Protocol));
 }