swww: add systemd service and wallpaper setter

dot_local/bin/executable_set-wallpapers.tmpl

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if ! command -v swww >/dev/null 2>&1; then
+  echo "swww not found in PATH" >&2
+  exit 1
+fi
+
+for _ in {1..50}; do
+  if swww query >/dev/null 2>&1; then
+    break
+  fi
+  sleep 0.1
+done
+
+if ! swww query >/dev/null 2>&1; then
+  echo "swww-daemon not responding" >&2
+  exit 1
+fi
+
+{{- range .monitors }}
+  {{- if .wallpaper }}
+swww img -o {{ .name }} "{{ .wallpaper }}"
+  {{- end }}
+{{- end }}