services: move .nix files into their own dirs

modules/services/mako/module.nix

@@ -0,0 +1,17 @@
+{pkgs, ...}: let
+  mako-wrapped = pkgs.symlinkJoin {
+    name = "mako-wrapped";
+    paths = [pkgs.mako];
+    buildInputs = [pkgs.makeWrapper];
+    postBuild = ''
+      wrapProgram $out/bin/mako --add-flags "\
+      --font 'Lexend 11' \
+      --border-radius 8 \
+      --padding 8 \
+      --border-size 5 \
+      --default-timeout 4000"
+    '';
+  };
+in {
+  environment.systemPackages = [mako-wrapped];
+}