refactor: consolidate app configurations and utility scripts

- Move 32+ app-specific scripts from features/apps/scripts/ to features/scripts/utils/ for centralized packaging.
- Create individual Nix modules for orphaned app configurations (btop, kitty, tmux, etc.) in features/apps/ using xdg.configFile.
- Fix broken paths in core/system/makima.nix and features/apps/vscode.nix.
- Update VSCode configuration to use the modern 'profiles.default.userSettings' API, resolving deprecation warnings.
- Merge duplicate 'nomarchy-launch-walker' scripts into a single robust utility.
- Remove stale root 'config/' directory.
- Update README.md and docs/creating-themes.md to reflect the new architecture and keybindings.
- Ensure all modules are correctly imported and verified via nix flake check.

features/scripts/utils/nomarchy-webapp-install

@@ -0,0 +1,89 @@
+#!/bin/bash
+
+set -e
+
+ICON_DIR="$HOME/.local/share/applications/icons"
+
+if (( $# < 3 )); then
+  echo -e "\e[32mLet's create a new web app you can start with the app launcher.\n\e[0m"
+  APP_NAME=$(gum input --prompt "Name> " --placeholder "My favorite web app")
+  APP_URL=$(gum input --prompt "URL> " --placeholder "https://example.com")
+  if [[ ! $APP_URL =~ ^[a-zA-Z][a-zA-Z0-9+.-]*: ]]; then
+    APP_URL="https://$APP_URL"
+  fi
+
+  # Try to fetch favicon automatically first.
+  FAVICON_URL="https://www.google.com/s2/favicons?domain=${APP_URL}&sz=128"
+  mkdir -p "$ICON_DIR"
+  if curl -fsSL -o "$ICON_DIR/$APP_NAME.png" "$FAVICON_URL" && [[ -s $ICON_DIR/$APP_NAME.png ]]; then
+    ICON_REF="$APP_NAME.png"
+  else
+    ICON_REF=$(gum input --prompt "Icon URL> " --placeholder "Could not fetch favicon automatically. Enter PNG icon URL (see https://dashboardicons.com)")
+  fi
+
+  CUSTOM_EXEC=""
+  MIME_TYPES=""
+  INTERACTIVE_MODE=true
+else
+  APP_NAME="$1"
+  APP_URL="$2"
+  if [[ ! $APP_URL =~ ^[a-zA-Z][a-zA-Z0-9+.-]*: ]]; then
+    APP_URL="https://$APP_URL"
+  fi
+  ICON_REF="$3"
+  CUSTOM_EXEC="$4" # Optional custom exec command
+  MIME_TYPES="$5"  # Optional mime types
+  INTERACTIVE_MODE=false
+fi
+
+# Ensure valid execution
+if [[ -z $APP_NAME || -z $APP_URL ]]; then
+  echo "You must set app name and app URL!"
+  exit 1
+fi
+
+# Resolve icon from URL or from a local icon name.
+mkdir -p "$ICON_DIR"
+
+if [[ -z $ICON_REF ]]; then
+  ICON_REF="https://www.google.com/s2/favicons?domain=${APP_URL}&sz=128"
+fi
+
+if [[ $ICON_REF =~ ^https?:// ]]; then
+  ICON_PATH="$ICON_DIR/$APP_NAME.png"
+  if ! curl -fsSL -o "$ICON_PATH" "$ICON_REF" || [[ ! -s $ICON_PATH ]]; then
+    echo "Error: Failed to download icon."
+    exit 1
+  fi
+else
+  ICON_PATH="$ICON_DIR/$ICON_REF"
+fi
+
+# Use custom exec if provided, otherwise default behavior
+EXEC_COMMAND="${CUSTOM_EXEC:-nomarchy-launch-webapp $APP_URL}"
+
+# Create application .desktop file
+DESKTOP_FILE="$HOME/.local/share/applications/$APP_NAME.desktop"
+
+cat >"$DESKTOP_FILE" <<EOF
+[Desktop Entry]
+Version=1.0
+Name=$APP_NAME
+Comment=$APP_NAME
+Exec=$EXEC_COMMAND
+Terminal=false
+Type=Application
+Icon=$ICON_PATH
+StartupNotify=true
+EOF
+
+# Add mime types if provided
+if [[ -n $MIME_TYPES ]]; then
+  echo "MimeType=$MIME_TYPES" >>"$DESKTOP_FILE"
+fi
+
+chmod +x "$DESKTOP_FILE"
+
+if [[ $INTERACTIVE_MODE == "true" ]]; then
+  echo -e "You can now find $APP_NAME using the app launcher (SUPER + SPACE)\n"
+fi