chore: Add package output to nix flake

.gitignore

@@ -1,2 +1,3 @@
 /target
+/result
 .direnv

flake.nix

@@ -15,18 +15,51 @@
             let
                 overlays = [ (import rust-overlay) ];
                 pkgs = import nixpkgs { inherit system overlays; };
+                lib = nixpkgs.lib;
                 rust = pkgs.rust-bin;
 
                 rustToolchain = rust.fromRustupToolchainFile ./rust-toolchain.toml;
                 rustNightlyToolchain = rust.selectLatestNightlyWith (t: t.minimal.override {
                     extensions = [ "rustfmt" ];
                 });
+                rustPlatform = pkgs.makeRustPlatform {
+                    cargo = rustToolchain;
+                    rustc = rustToolchain;
+                };
 
                 buildTools = [
                     rustToolchain
                     rustNightlyToolchain
                 ];
+
+                manifest = lib.importTOML ./Cargo.toml;
+                packageName = manifest.package.name;
+                packageVersion = manifest.package.version;
+
+                package = rustPlatform.buildRustPackage {
+                    nativeBuildInputs = buildTools;
+
+                    pname = packageName;
+                    version = packageVersion;
+                    src = lib.cleanSource ./.;
+
+                    verbose = true;
+
+                    cargoLock = {
+                        lockFile = ./Cargo.lock;
+                        allowBuiltinFetchGit = true;
+                    };
+
+                    meta = {
+                        mainProgram = packageName;
+                    };
+                };
             in {
+                packages = {
+                    default = package;
+                    ${packageName} = package;
+                };
+
                 devShells.default = pkgs.mkShell {
                     name = "projtool";