hosts/carbon: Add scan-to-gpg

flake/overlay.nix

@@ -4,6 +4,7 @@
 , chaosevents
 , harmonia
 , nurausstieg
+, scan-to-gpg
 , ssh-to-age
 , ...
 }@inputs:
@@ -19,6 +20,8 @@ final: prev: {
   };
   inherit (nurausstieg.packages.${final.system})
     nurausstieg;
+  inherit (scan-to-gpg.packages.${final.system})
+    scan-to-gpg;
   inherit (ssh-to-age.packages.${final.system})
     ssh-to-age;
 }