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/install.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Install Breeze-style tray icons for Ngó Sen. Usage: sudo ./install.sh
+set -euo pipefail
+here=$(cd "$(dirname "$0")" && pwd)
+ROOT=${ROOT:-}   # for dry-run testing only
+[[ $EUID -eq 0 || -n $ROOT ]] || { echo "Must be run with sudo"; exit 1; }
+owner=${SUDO_USER:-$(id -un "${PKEXEC_UID:-0}")}
+dest=$ROOT/usr/local/share/ngosen-breeze-icons
+
+install -d "$dest/icons"
+install -m644 "$here"/icons/*.svg "$dest/icons/"
+install -m755 "$here/apply.sh" "$dest/apply.sh"
+install -Dm644 "$here/ngosen-breeze-icons.hook" "$ROOT/etc/pacman.d/hooks/ngosen-breeze-icons.hook"
+# Older versions used NoUpgrade in pacman.conf; the hook replaces it
+sed -i '/^# ngosen-breeze-icons$/,+1d' "$ROOT/etc/pacman.conf"
+ROOT=$ROOT "$dest/apply.sh"
+
+# Ngó Sen: use the monochrome icons (not the lotus ones), white for a dark panel
+conf=$ROOT$(getent passwd "$owner" | cut -d: -f6)/.config/fcitx5/conf/ngosen.conf
+as_owner() { if [[ -n $ROOT ]]; then "$@"; else runuser -u "$owner" -- "$@"; fi; }
+if [[ -f $conf ]]; then
+  for kv in UseLotusIcons=False IconTheme=Dark; do
+    k=${kv%%=*}
+    if grep -q "^$k=" "$conf"; then as_owner sed -i "s/^$k=.*/$kv/" "$conf"
+    elif grep -q "^# $k=" "$conf"; then as_owner sed -i "s/^# $k=.*/$kv/" "$conf"
+    else as_owner sh -c "echo '$kv' >> '$conf'"; fi
+  done
+else
+  as_owner install -Dm600 /dev/stdin "$conf" <<<$'UseLotusIcons=False\nIconTheme=Dark'
+fi
+
+echo "Done. Restart fcitx5 and plasmashell (without sudo):"
+echo "  $here/restart-fcitx5.sh; systemctl --user restart plasma-plasmashell"