feat(niri): split config into modules and port hyprlua keybinds
Split monolithic config.kdl into modules/ (input, outputs, layout,
animations, environment, autostart, window-rules, binds), mirroring
the hyprlua modular structure.
Keybind additions and fixes:
- Port all missing hyprlua binds (Mod+0, mouse drag/resize, Mod+Ctrl+M,
Mod+Shift+Return→overview, Mod+Shift+Alt group move aliases)
- Enforce modifier semantics: Shift=move window, Ctrl=workspace,
Alt=resize across all directional keys
- Add Mod+Ctrl+J/K/Down/Up → focus-workspace-down/up
- Add Mod+Ctrl+Shift+J/K/Down/Up → move-column-to-workspace-down/up
- Fix Mod+Ctrl+K/Up (was toggle-overview, now focus-workspace-up)
- Fix Mod+Ctrl+Shift+Up (was move-to-recent, now move-to-workspace-up)
- Relocate toggle-overview to Mod+Ctrl+Space
- Remove Mod+Shift+Alt+* aliases (violated Alt=resize rule)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>