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/scripts/nomarchy-font-current

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# Returns the name of the current monospace font being used by extracting it from the Waybar stylesheet.
+# This can be changed using nomarchy-font-set.
+
+grep -oP 'font-family:\s*["'\'']?\K[^;"'\'']+' ~/.config/waybar/style.css | head -n1