add image generation

Signed-off-by: ahuston-0 <aliceghuston@gmail.com>

hydra/jobs.nix

@@ -3,8 +3,15 @@ let
   inherit (inputs.nixpkgs.lib) mapAttrs;
 
   getCfg = _: cfg: cfg.config.system.build.toplevel;
+  getFormat =
+    _: cfg: format:
+    cfg.config.formats.${format};
+  imageWrapper = format: mapAttrs getFormat outputs.nixosConfigurations format;
 in
 {
   inherit (outputs) formatter devShells;
   hosts = mapAttrs getCfg outputs.nixosConfigurations;
+  install-isos = imageWrapper "install-iso";
+  isos = imageWrapper "iso";
+  qcow = imageWrapper "qcow";
 }