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-battery-capacity

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# Returns the battery full capacity in Wh (rounded to whole number).
+# Used by nomarchy-battery-status for displaying battery capacity.
+
+battery_info=$(upower -i $(upower -e | grep BAT))
+
+echo "$battery_info" | awk '/energy-full:/ {
+    printf "%d", $2
+    exit
+}'