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/system/scripts/nomarchy-hw-match

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# Match against the computer's DMI product name (case-insensitive).
+# Usage: nomarchy-hw-match "XPS"
+
+grep -qi "$1" /sys/class/dmi/id/product_name 2>/dev/null