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/summer-night/colors.toml

@@ -0,0 +1,23 @@
+accent = "#83b6af"
+cursor = "#d3c6aa"
+foreground = "#d3c6aa"
+background = "#2d353b"
+selection_foreground = "#d3c6aa"
+selection_background = "#505a60"
+
+color0 = "#3c474d"
+color1 = "#e68183"
+color2 = "#a7c080"
+color3 = "#d9bb80"
+color4 = "#83b6af"
+color5 = "#d39bb6"
+color6 = "#87c095"
+color7 = "#868d80"
+color8 = "#868d80"
+color9 = "#e68183"
+color10 = "#a7c080"
+color11 = "#d9bb80"
+color12 = "#83b6af"
+color13 = "#d39bb6"
+color14 = "#87c095"
+color15 = "#868d80"