Fix build: synchronize Request API, fix GmailSynchronizer, and migrate UI to Qt6 Widgets

src/ui/models/EmailListModel.cpp

@@ -3,8 +3,7 @@
 #include <QDateTime>
 
 EmailListModel::EmailListModel(QObject *parent)
-    : QAbstractListModel(parent),
-      m_mailItemDao(MailItemDao::instance())
+    : QAbstractListModel(parent)
 {
     refresh();
 }
@@ -89,9 +88,9 @@ void EmailListModel::refresh()
 {
     beginResetModel();
     if (m_folderId == -1) {
-        m_emails = m_mailItemDao.findAll();
+        m_emails = MailItemDao::findAll();
     } else {
-        m_emails = m_mailItemDao.findByFolderId(m_folderId);
+        m_emails = MailItemDao::findByFolderId(m_folderId);
     }
     endResetModel();
     qDebug() << "EmailListModel refreshed with" << m_emails.size() << "emails for folderId" << m_folderId;