Add base docker image

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

flake.nix

@@ -26,6 +26,7 @@
         treefmt = inputs.treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
       in
       {
+        packages.${system} = import ./packages { inherit pkgs; };
         formatter.${system} = treefmt.config.build.wrapper;
         checks.${system}.formatting = treefmt.config.build.check inputs.self;
       }