Added
- Tabbed Editing: Custom-drawn Edge-like tab bar with rounded top corners, shrink-to-fit sizing with ellipsis truncation, per-tab close buttons, hover highlighting, and dark/light theme support. Keyboard shortcuts: Ctrl+T (new tab), Ctrl+W (close tab), Ctrl+PageUp/Down (switch tabs). Multi-file open dialog when tabs are enabled. Configurable in Settings.
- Session Restore: Persist open documents across app restarts with three modes configurable in Settings: Off (default), Saved Files Only, and Full (including unsaved content). Supports multi-instance session merging so closing one window doesn't erase another's tabs.
- Dynamic Line Number Gutter: Line number column auto-sizes based on document line count, properly supporting files with 100,000+ lines.