make image.nix a first-class module

flake.nix

@@ -92,7 +92,7 @@
     #   boot, checkout this flake into /etc/nixos AND UPDATE THE UUIDS IT REFERENCES.
     #   then `nixos-rebuild ...`
     decl-img = { name, system, extraModules ? [] }: (
-      (self.decl-machine { inherit name system; extraModules = extraModules ++ [./image.nix]; })
+      (self.decl-machine { inherit name system extraModules; })
         .config.system.build.img
     );
 

modules/default.nix

@@ -4,6 +4,7 @@
   imports = [
     ./gui
     ./hardware
+    ./image.nix
     ./impermanence.nix
     ./services/duplicity.nix
     ./universal