put flatpak service where it's supposed to be

demilich/services.nix

@@ -1,10 +1,6 @@
 { config, pkgs, ... }:
 {
   systemd = {
-    flatpak = {
-      enable = true;
-    };
-
     user = {
       services = {
         niri = {
@@ -49,6 +45,10 @@
   };
 
   services = {
+    flatpak = {
+      enable = true;
+    };
+
     tailscale = {
       enable = true;
     };