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

core/default.nix

@@ -0,0 +1,20 @@
+{ config, lib, pkgs, ... }:
+
+{
+  imports = [
+    ./system/options.nix
+    ./system/state.nix
+    ./system/systemd.nix
+    ../themes/engine/plymouth.nix
+    ../themes/engine/sddm.nix
+    ./system/hardware.nix
+    ./system/audio.nix
+    ./system/bluetooth.nix
+    ./system/network.nix
+    ../features/apps/browser.nix
+    ./system/impermanence.nix
+    ../features/apps/makima.nix
+  ];
+
+  time.timeZone = lib.mkDefault config.nomarchy.system.timezone;
+}