feat: responsive compact mail view + folder unread badges

- CompactMailDelegate: card-based view for narrow panels (<420px)
  * Avatar with hash-based color, sender + date (relative format)
  * Subject line with attachment icon
  * Action buttons: flag, delete, category, more (context menu)
  * Unread highlight with light blue background + bold sender
- MailListView: automatic switch between tree/table (wide) and list/cards (narrow)
  * QStackedWidget with QTreeView + QListView sharing same proxy model
  * resizeEvent threshold at 420px
  * Signals forwarded to MainMainWindow for actions
- FolderTreeDelegate: custom paint for folder tree
  * Unread count badge (blue pill) right-aligned on folder nodes
  * Account nodes bold, folder nodes normal weight
  * Proper indentation per depth level
- MailItemDao::countUnreadByFolderId() for real-time unread counts
- MainMainWindow handlers for compact actions (flag, delete, category, more menu)

build/wino-mail-qt_autogen/J6PSKMGISE/moc_EmailListModel.cpp

@@ -51,7 +51,7 @@ template <> constexpr inline auto EmailListModel::qt_create_metaobjectdata<qt_me
             qt_methods, qt_properties, qt_enums);
 }
 Q_CONSTINIT const QMetaObject EmailListModel::staticMetaObject = { {
-    QMetaObject::SuperData::link<QAbstractListModel::staticMetaObject>(),
+    QMetaObject::SuperData::link<QAbstractTableModel::staticMetaObject>(),
     qt_staticMetaObjectStaticContent<qt_meta_tag_ZN14EmailListModelE_t>.stringdata,
     qt_staticMetaObjectStaticContent<qt_meta_tag_ZN14EmailListModelE_t>.data,
     qt_static_metacall,
@@ -79,12 +79,12 @@ void *EmailListModel::qt_metacast(const char *_clname)
     if (!_clname) return nullptr;
     if (!strcmp(_clname, qt_staticMetaObjectStaticContent<qt_meta_tag_ZN14EmailListModelE_t>.strings))
         return static_cast<void*>(this);
-    return QAbstractListModel::qt_metacast(_clname);
+    return QAbstractTableModel::qt_metacast(_clname);
 }
 
 int EmailListModel::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
 {
-    _id = QAbstractListModel::qt_metacall(_c, _id, _a);
+    _id = QAbstractTableModel::qt_metacall(_c, _id, _a);
     return _id;
 }
 QT_WARNING_POP