- Add Keywords field from desktop files to searchable tags
(fixes apps like Nautilus not found when searching by legacy name)
- Respect XDG_DATA_DIRS with proper fallbacks for app directories
- Add Flatpak, Snap, and Nix application directory support
- Simplify desktop file launch to use gio directly (guaranteed by GTK4)
- Add desktop notifications for launch failures
- Check desktop file existence before launch attempt