refactor: group stow packages into common, mac and kde

Split the packages by platform so each app stays an opt-in Stow package
under common/, mac/ or kde/. KDE gets its own Fastfetch, Helium and
Spectacle packages, and darwin-breeze becomes kde/theme. The READMEs
document stowing a whole group as well as individual packages.

kde/tray-icons/.local/share/ngosen-breeze-icons/restore.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+# Put Ngó Sen's original icons back and remove the hook. Usage: sudo ./restore.sh
+set -euo pipefail
+ROOT=${ROOT:-}   # for dry-run testing only
+[[ $EUID -eq 0 || -n $ROOT ]] || { echo "Must be run with sudo"; exit 1; }
+dest=$ROOT/usr/local/share/ngosen-breeze-icons
+[[ -d $dest/orig/usr ]] || { echo "No original icons in $dest/orig"; exit 1; }
+(cd "$dest/orig" && find usr -name '*.svg' -print0) | while IFS= read -r -d '' f; do
+  install -m644 "$dest/orig/$f" "$ROOT/$f"
+done
+rm -f "$ROOT/etc/pacman.d/hooks/ngosen-breeze-icons.hook"
+rm -rf "$dest"
+echo "Restored. To get the lotus icons back, turn them on in Ngó Sen Settings."
+echo "Restart plasmashell (without sudo):  systemctl --user restart plasma-plasmashell"