Add tests for LtsTimelineClassic Item, TimelineView, TimelineWidget, TimelineIndicator

- test_item.cpp: 3 tests for Item class
- test_timelineview.cpp: 3 tests for TimelineView class
- test_timelinewidget.cpp: 3 tests for TimelineWidget class
- test_timelineindicator.cpp: 3 tests for TimelineIndicator class

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

qt6-after/qt6-migrated-benchmark/tests/test_timelinewidget.cpp

@@ -0,0 +1,39 @@
+#include "Lts/Common/LtsTimelineClassic/TimelineWidget.h"
+
+#include <QWidget>
+#include <gtest/gtest.h>
+
+namespace LtsTimelineClassic
+{
+
+class TimelineWidgetTest : public ::testing::Test
+{
+  protected:
+    void SetUp() override {}
+
+    void TearDown() override {}
+};
+
+TEST(TimelineWidgetTest, HeaderCompilesAndLinks)
+{
+    // Verify header compiles without errors
+    EXPECT_TRUE(true);
+}
+
+TEST(TimelineWidgetTest, CanInstantiateTimelineWidget)
+{
+    // Basic instantiation test
+    QWidget parent;
+    TimelineWidget timelineWidget(&parent);
+    EXPECT_NO_THROW(timelineWidget.update());
+}
+
+TEST(TimelineWidgetTest, TimelineWidgetHasValidState)
+{
+    QWidget parent;
+    TimelineWidget timelineWidget(&parent);
+    // Test basic properties
+    EXPECT_NO_THROW(timelineWidget.setGeometry(0, 0, 1024, 768));
+}
+
+} // namespace LtsTimelineClassic