- EmailTreeModel: hierarchical model for grouped email view (QTreeView)
- DateGroupProxyModel: proxy model for date-based grouping logic
- MailListView: migrated from QTableView to QTreeView with grouping support
- ReaderView: subject frame with shadow, avatar moved to header, body inside header
- MainWindow: frameless with rounded corners, 1px border, edge resize, no status bar
- Stability fixes for grouping mode switch:
* Proper tree cleanup (no double-delete of root)
* Bounds checking on all array accesses
* Null pointer checks in index/parent/data methods
* Date validity checks before grouping
* Index validation before accessing m_emails
javier
2281b01f49