- SettingsView: complete UI with tabs for Accounts, Categories, Rules, Templates, Signatures, General, Appearance
- Categories: QTreeWidget with hierarchical view, color picker, parent categories
- Rules: QListWidget with RuleEditorDialog integration, toggle enabled
- Templates: QListWidget with TemplateEditorDialog integration
- Signatures: QListWidget with SignatureEditorDialog integration
- SignatureDao: full CRUD with default signature support
- common_structs.h: QColor for Category, all structs centralized
- icons.qrc: updated with Linear/Outline/Bold icons from resources
- Category: QColor instead of QString for color
- EmailTreeModel/DateGroupProxyModel: email grouping by date
- MailListView: QTreeView with date grouping combo
- ReaderView: subject frame with shadow, avatar in header, body inside header
- MainWindow: frameless with rounded corners, 1px border, edge resize, no status bar
- icons.qrc: complete icon set from resources/icons/SVG
- 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