- MailListView: ExtendedSelection mode for both tree and list views
- Action bar (blue bar) appears when items selected
- Select all checkbox + counter label
- Batch actions: Flag, Mark unread, Move (TODO), Delete, Exit selection
- Signals: selectionChanged, batchFlagRequested, batchDeleteRequested, batchMarkUnreadRequested, batchMoveRequested
- enterMultiSelectMode()/exitMultiSelectMode() state management
- Works in both normal and compact views
javier
43b828fe87