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-toggle-nightlight

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+# Toggles the nightlight (hyprsunset).
+# Hybrid: updates state.json and provides instant feedback.
+
+STATE_DIR="$HOME/.config/nomarchy"
+STATE_FILE="$STATE_DIR/state.json"
+mkdir -p "$STATE_DIR"
+
+# Initialize if doesn't exist
+[[ ! -f $STATE_FILE ]] && echo "{}" > "$STATE_FILE"
+
+if [[ $NOMARCHY_TOGGLE_NIGHTLIGHT == "false" ]]; then
+    NEW_VALUE="true"
+    hyprctl dispatch exec hyprsunset --temperature 4000
+    notify-send -u low "  Nightlight enabled"
+else
+    NEW_VALUE="false"
+    pkill hyprsunset
+    notify-send -u low "  Nightlight disabled"
+fi
+
+TMP_JSON=$(mktemp)
+jq --argjson val "$NEW_VALUE" '.nightlight = $val' "$STATE_FILE" > "$TMP_JSON" && mv "$TMP_JSON" "$STATE_FILE"
+
+echo "Nightlight state set to $NEW_VALUE. Environment will be fully updated on next rebuild."