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/desktop/nightlight.nix

@@ -0,0 +1,11 @@
+{ config, lib, ... }:
+
+let
+  temp = toString (if config.nomarchy.toggles.nightlight then config.nomarchy.nightlightTemperature else 6500);
+in
+{
+  services.hyprsunset = {
+    enable = lib.mkDefault true; # Always enabled, we control via IPC and state
+    extraArgs = lib.mkDefault [ "--temperature" temp ];
+  };
+}