Update to (somewhat?) dendritic pattern

Heavily inspired by https://github.com/Doc-Steve/dendritic-design-with-flake-parts.

> Atomic commits? Never heard of them!

modules/factory/hyprpaper.nix

@@ -0,0 +1,19 @@
+{
+  config.flake.factory.hyprpaper =
+    { wallpaper_path
+    , monitor_names
+    ,
+    }: { config, ... }: {
+      services.hyprpaper =
+        /*
+      TODO: assert that hyprland is enabled
+        */
+        {
+          enable = true;
+          settings = {
+            preload = [ wallpaper_path ];
+            wallpaper = map (mon: "mon,${wallpaper_path}") monitor_names;
+          };
+        };
+    };
+}