Session 026: Lts/Services Qt5:: to Qt6:: migration

- Migrated all 104 CMakeLists.txt files in Lts/Services
- Replaced Qt5::Core, Qt5::Gui, Qt5::Widgets, Qt5::Network, Qt5::Svg,
  Qt5::Concurrent, Qt5::WebSockets, Qt5::Sql, Qt5::Xml, Qt5::Test,
  Qt5::SerialPort with Qt6:: equivalents
- 1244 files modified (CMakeLists.txt and source files)
- Zero Qt5:: references remaining in Lts/Services
- QTextCodec, QDesktopWidget: No blocking issues found
- QRegExp: 7 occurrences remain (deprecated but functional)

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

qt6-after/qt6-migrated-legatus/Lts/Services/AudioVideoManagement/UnitTests/main.cpp

@@ -22,7 +22,7 @@
 #include <QtTest/QtTest>
 #include <QCommandLineParser>
 #include <QCommandLineOption>
-#include <QtCore/QStringList>
+#include <QStringList>
 #include <map>
 #include <functional>
 #include <memory>