Migrate LTS Tools Group 6 (D&L) to Qt6

Build script changes:
- Add --group6/--no-group6 argument support to new_docker_build.sh
- Add GROUP6_TARGETS array with 11 LTS tools
- Add BUILD_GROUP6 environment variable export
- Add GROUP6 build invocation in run_build_group function

Test infrastructure:
- Create CTest test files for all 11 Group 6 tools
- Add exclusion filters in tests/CMakeLists.txt for conditional builds
- Tests follow gtest pattern: CompilationStub, Qt6ApiCompatibility, BasicFunctionality

Qt6 migration bug fixes:
- DBAdministration: Fix m_id → id member access (3 files)
- DBAdministration: Add missing QFile include in showLogFile.cpp
- DBUpdate: Add CMAKE_AUTOUIC_SEARCH_PATHS for ui/ directory
- DBUpdate: Fix m_id → id, m_description → description (3 files)

Build validation:
- DBAdministration, DBOperatorSettingsRemover, DBUpdate build successfully
- Remaining tools blocked by pre-existing Group 3 (ExerciseManagement) errors
- Policy checks passed

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

qt6-after/qt6-migrated-legatus/Lts/Tools/DBUpdate/exercises_model.cpp

@@ -51,13 +51,13 @@ bool ExercisesModel::initModel(const QSqlDatabase &db, const QString &version, c
   while (q.next())
   {
     ExerciseUpdate e;
-    e.m_id        = q.value(0).toInt();
+    e.id        = q.value(0).toInt();
     e.name      = q.value(1).toString();
     e.startTime = q.value(2).toLongLong();
     e.endTime   = q.value(3).toLongLong();
     e.stateId   = q.value(4).toInt();
 
-    e.schema    = QStringLiteral("EX_")+QString::number(e.m_id);
+    e.schema    = QStringLiteral("EX_")+QString::number(e.id);
     e.isChecked = false;
 
     QString stmt_db = QStringLiteral("SELECT id, version, description, updated, success FROM ") + e.schema +
@@ -67,7 +67,7 @@ bool ExercisesModel::initModel(const QSqlDatabase &db, const QString &version, c
     if (q1.execAndFetch(stmt_db))
     {
       e.version     = q1.value(1).toString();
-      e.m_description = q1.value(2).toString();
+      e.description = q1.value(2).toString();
       e.updated     = q1.value(3).toLongLong();
 
     }
@@ -115,7 +115,7 @@ QVariant ExercisesModel::data(const QModelIndex &index, int role) const
     switch (index.column())
     {
     case Id:
-      return e.m_id;
+      return e.id;
     case Name:
       return QString(e.name);
     case StartTime:
@@ -127,7 +127,7 @@ QVariant ExercisesModel::data(const QModelIndex &index, int role) const
     case Version:
       return e.version;
     case Description:
-      return e.m_description;
+      return e.description;
     case Updated:
       return DTG::toStringMSec(e.updated);
     case Schema: