refactor: implement component-based architecture for enhanced maintainability

- Reorganize directory structure into core/, features/, and themes/
- Colocate application Nix logic, configs, scripts, and theme overrides
- Implement 'Inversion of Control' for theming: apps now pull theme-specific layouts
- Update flake.nix and shared library paths to match the new structure
- Document the new Feature-Centric architecture in README.md

core/home/config/nomarchy/default/alacritty/screensaver.toml

@@ -0,0 +1,11 @@
+[colors.primary]
+background = "0x000000"
+
+[colors.cursor]
+cursor = "0x000000"
+
+[font]
+size = 18.0
+
+[window]
+opacity = 1.0