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

features/apps/scripts/nomarchy-launch-editor

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# Launch the default editor as determined by $EDITOR (set via ~/.config/uwsm/default) (or nvim if missing).
+# Starts suitable editors in a terminal window and otherwise as a regular application.
+
+nomarchy-cmd-present "$EDITOR" || EDITOR=nvim
+
+case "$EDITOR" in
+nvim | vim | nano | micro | hx | helix | fresh)
+  exec nomarchy-launch-tui "$EDITOR" "$@"
+  ;;
+*)
+  exec setsid uwsm-app -- "$EDITOR" "$@"
+  ;;
+esac