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/switcher.nix

@@ -0,0 +1,64 @@
+{ config, pkgs, lib, ... }:
+
+let
+  nomarchyLib = import ../lib { inherit lib; };
+  themeList = builtins.concatStringsSep "\\n" nomarchyLib.themeNames;
+
+  nomarchy-theme-selector = pkgs.writeShellScriptBin "nomarchy-theme-selector" ''
+    SELECTED_THEME=$(echo -e "${themeList}" | walker --dmenu)
+
+    if [ -n "$SELECTED_THEME" ]; then
+      nomarchy-theme-set "$SELECTED_THEME"
+    fi
+  '';
+
+  nomarchy-font-selector = pkgs.writeShellScriptBin "nomarchy-font-selector" ''
+    STATE_DIR="${config.home.homeDirectory}/.config/nomarchy"
+    STATE_FILE="$STATE_DIR/state.json"
+
+    mkdir -p "$STATE_DIR"
+    [[ ! -f $STATE_FILE ]] && echo "{}" > "$STATE_FILE"
+
+    # Simple list of common nerd fonts, could be expanded
+    FONTS="JetBrainsMono Nerd Font\nRobotoMono Nerd Font\nFiraCode Nerd Font\nUbuntuMono Nerd Font"
+    SELECTED_FONT=$(echo -e "$FONTS" | walker --dmenu)
+
+    if [ -n "$SELECTED_FONT" ]; then
+      TMP_JSON=$(mktemp)
+      jq --arg font "$SELECTED_FONT" '.font = $font' "$STATE_FILE" > "$TMP_JSON" && mv "$TMP_JSON" "$STATE_FILE"
+      env-update
+    fi
+  '';
+
+  nomarchy-wallpaper-selector = pkgs.writeShellScriptBin "nomarchy-wallpaper-selector" ''
+    STATE_DIR="${config.home.homeDirectory}/.config/nomarchy"
+    STATE_FILE="$STATE_DIR/state.json"
+    THEMES_DIR="${config.xdg.dataHome}/nomarchy/themes"
+
+    mkdir -p "$STATE_DIR"
+    [[ ! -f $STATE_FILE ]] && echo "{}" > "$STATE_FILE"
+
+    # List all images in all themes backgrounds
+    # We search in the system-wide flake source for distro wallpapers to avoid Nix Store bloat
+    WALLPAPERS=$(find "${config.xdg.dataHome}/nomarchy/themes" -type f \( -name "*.jpg" -o -name "*.png" \) 2>/dev/null)
+    DISTRO_THEMES="/etc/nixos/nomarchy/assets/themes"
+    if [ -d "$DISTRO_THEMES" ]; then
+        WALLPAPERS="$WALLPAPERS\n$(find "$DISTRO_THEMES" -type f \( -name "*.jpg" -o -name "*.png" \))"
+    fi
+    # Include user themes if they exist
+    if [ -d "${config.home.homeDirectory}/.config/nomarchy/themes" ]; then
+        WALLPAPERS="$WALLPAPERS\n$(find "${config.home.homeDirectory}/.config/nomarchy/themes" -type f \( -name "*.jpg" -o -name "*.png" \))"
+    fi
+    SELECTED_WP=$(echo -e "$WALLPAPERS" | walker --dmenu)
+
+    if [ -n "$SELECTED_WP" ]; then
+      TMP_JSON=$(mktemp)
+      jq --arg wp "$SELECTED_WP" '.wallpaper = $wp' "$STATE_FILE" > "$TMP_JSON" && mv "$TMP_JSON" "$STATE_FILE"
+      swww img "$SELECTED_WP" --transition-type outer --transition-pos 0.85,0.97 --transition-step 90 &
+      env-update
+    fi
+  '';
+in
+{
+  home.packages = [ nomarchy-theme-selector nomarchy-font-selector nomarchy-wallpaper-selector ];
+}