feat: add basic docker image build

docker.nix

@@ -0,0 +1,9 @@
+{ dockerTools, my-crate }:
+dockerTools.buildLayeredImage {
+  name = my-crate.pname;
+  tag = "latest";
+
+  contents = [ my-crate ];
+
+  config.Cmd = [ ("/bin/" + my-crate.pname) ];
+}

flake.nix

@@ -123,6 +123,8 @@
           my-crate-llvm-coverage = craneLibLLvmTools.cargoLlvmCov (commonArgs // {
             inherit cargoArtifacts;
           });
+
+          docker-image = pkgs.callPackage ./docker.nix { inherit my-crate; };
         };
 
         apps.default = flake-utils.lib.mkApp {