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/engine/sddm.nix

@@ -0,0 +1,43 @@
+{ config, pkgs, lib, ... }:
+
+let
+  nomarchy-sddm-theme = pkgs.stdenv.mkDerivation {
+    pname = "nomarchy-sddm-theme";
+    version = "1.0";
+    src = ./sddm/nomarchy;
+    nativeBuildInputs = [ pkgs.libsForQt5.qt5.wrapQtAppsHook ];
+    installPhase = ''
+      mkdir -p $out/share/sddm/themes/nomarchy
+      cp -r * $out/share/sddm/themes/nomarchy/
+    '';
+    propagatedBuildInputs = with pkgs.libsForQt5.qt5; [
+      qtgraphicaleffects
+      qtquickcontrols2
+      qtsvg
+    ];
+  };
+in
+{
+  services.xserver.enable = lib.mkDefault true;
+  services.displayManager.sddm = {
+    enable = lib.mkDefault true;
+    wayland.enable = lib.mkDefault true;
+    theme = lib.mkDefault "nomarchy";
+  };
+
+  services.displayManager.defaultSession = lib.mkDefault "hyprland-uwsm";
+
+  services.displayManager.autoLogin = {
+    enable = lib.mkDefault true;
+    user = lib.mkDefault "nomarchy";
+  };
+
+  environment.systemPackages = lib.mkDefault [ nomarchy-sddm-theme ];
+
+  # Enable Hyprland system-level dependencies
+  programs.hyprland = {
+    enable = lib.mkDefault true;
+    withUWSM = lib.mkDefault true;
+  };
+  programs.uwsm.enable = lib.mkDefault true;
+}