feat: add Home Manager refactoring plan and initial structure

- Add comprehensive Home Manager refactoring plan document
- Create initial Home Manager directory structure with user configs
- Add modular Emacs configuration for Home Manager integration
- Update system configurations for Home Manager compatibility
- Preserve existing functionality while preparing for migration

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

machines/little-rascal/configuration.nix

@@ -17,7 +17,7 @@
 
     # Desktop
     ../../modules/desktop/niri.nix
-    ../../modules/desktop/waybar.nix
+    # ../../modules/desktop/waybar.nix
     ../../modules/desktop/gnome.nix
     ../../modules/desktop/cosmic.nix
     ../../modules/desktop/fonts.nix