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-set

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# Set the system-wide monospace font that should be used by the terminal, hyprlock, waybar, swayosd, etc.
+# Declarative version for Nomarchy NixOS.
+
+font_name="$1"
+
+if [[ -z $font_name ]]; then
+  echo "Usage: nomarchy-font-set <font-name>"
+  exit 1
+fi
+
+STATE_DIR="$HOME/.config/nomarchy"
+STATE_FILE="$STATE_DIR/state.json"
+
+mkdir -p "$STATE_DIR"
+[[ ! -f $STATE_FILE ]] && echo "{}" > "$STATE_FILE"
+
+if fc-list | grep -iq "$font_name"; then
+  TMP_JSON=$(mktemp)
+  jq --arg font "$font_name" '.font = $font' "$STATE_FILE" > "$TMP_JSON" && mv "$TMP_JSON" "$STATE_FILE"
+  echo "Font set to $font_name declaratively. Applying changes..."
+  env-update
+
+  # Instant feedback for certain apps via IPC
+  if pgrep -x kitty; then
+    pkill -USR1 kitty
+  fi
+  if pgrep -x ghostty; then
+    pkill -SIGUSR2 ghostty
+    notify-send -u low "    You must restart Ghostty to see font change"
+  fi
+
+  nomarchy-hook font-set "$font_name"
+else
+  echo "Font '$font_name' not found."
+  exit 1
+fi