style: Apply clang-format to all C++ files

- Format MainWindow.cpp, MainWindow.h, main.cpp
- Format test files (test_main.cpp, test_mainwindow.cpp)
- Fixes Jenkins clang-format policy check

Entire-Checkpoint: ea47c089bf3a

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

@@ -1,12 +1,13 @@
-#include <QtTest/QtTest>
-#include <QApplication>
 #include "MainWindow.h"
 
+#include <QApplication>
+#include <QtTest/QtTest>
+
 class TestMainWindowWidget : public QObject
 {
     Q_OBJECT
 
-private slots:
+  private slots:
     void testMainWindowCreation();
     void testWindowTitle();
     void testValidateInputMethod();
@@ -28,7 +29,7 @@ void TestMainWindowWidget::testWindowTitle()
 void TestMainWindowWidget::testValidateInputMethod()
 {
     MainWindow window;
-    
+
     QVERIFY(window.validateInput(u"Test123"_s));
     QVERIFY(window.validateInput(u"abc456"_s));
     QVERIFY(!window.validateInput(u"123Test"_s));