Replace vim-lumen with custom solution that automatically switches between
ayu (dark) and everforest (light) colorschemes based on system theme.

- macOS: uses defaults read -g AppleInterfaceStyle
- Linux: checks gsettings, kreadconfig5, and COLORFGBG
- Polls every 3 seconds for theme changes
- Provides :RefreshTheme command for manual switching

Uses the importer module with extraModules to enable clan.core.state-version,
which provides automatic state version management for all machines.

Configures the state-version clan service for all machines using the
inventory.instances configuration as documented in clan-core.