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

themes/palettes/gruvbox/colors.toml

@@ -0,0 +1,23 @@
+accent = "#7daea3"
+cursor = "#bdae93"
+foreground = "#d4be98"
+background = "#282828"
+selection_foreground = "#ebdbb2"
+selection_background = "#d65d0e"
+
+color0 = "#3c3836"
+color1 = "#ea6962"
+color2 = "#a9b665"
+color3 = "#d8a657"
+color4 = "#7daea3"
+color5 = "#d3869b"
+color6 = "#89b482"
+color7 = "#d4be98"
+color8 = "#3c3836"
+color9 = "#ea6962"
+color10 = "#a9b665"
+color11 = "#d8a657"
+color12 = "#7daea3"
+color13 = "#d3869b"
+color14 = "#89b482"
+color15 = "#d4be98"