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

features/apps/chromium/config/Default/Preferences

@@ -0,0 +1,15 @@
+{
+  "extensions": {
+    "theme": {
+      "id": "",
+      "use_system": false,
+      "use_custom": false
+    }
+  },
+  "browser": {
+    "theme": {
+      "color_scheme": 2,
+      "user_color": 2
+    }
+  }
+}