- CentralWidget with bottom-left/bottom-right radius 8px
- Event filter on central widget to forward mouse events for resize
- Consolidated windowFlags (Qt::Window | Frameless | MinMax | Close)
- setMouseTracking(true) for cursor updates
- Removed WA_TranslucentBackground causing black corners
- Status bar fully removed (setStatusBar(nullptr))
- ReaderView: complete rewrite with CSS styling, headers, attachments, zoom, find, dark mode, image blocking
- Categories: DAO + UI tree widget with colors, nested categories, assignment
- Rules engine: DAO + evaluation + actions (move, mark read, flag, delete, category, forward)
- Templates: DAO + editor + manager with variables support
- Signatures: DAO + manager + auto-per-account + manual selector in compose
- ComposeView: signature combo, template selector, auto-signature on new email
- MainWindow: frameless with rounded corners, 1px border, resize from edges, no status bar
- Database: new tables (Category, MailCategory, Rule, Template, Signature) with indexes
javier