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/home/config/uwsm/default

@@ -0,0 +1,13 @@
+# Changes require a restart to take effect.
+
+# Install other terminals via Install > Terminal
+export TERMINAL=xdg-terminal-exec
+
+# Use code for VSCode
+export EDITOR=nvim
+
+# Use a custom directory for screenshots (remember to make the directory!)
+# export OMARCHY_SCREENSHOT_DIR="$HOME/Pictures/Screenshots"
+
+# Use a custom directory for screenrecordings (remember to make the directory!)
+# export OMARCHY_SCREENRECORD_DIR="$HOME/Videos/Screencasts"