feat: Add nix installer (closes #2)

Author: rober-m

.gitignore

@@ -8,3 +8,5 @@ yaci-cli.history
 logs/
 
 .direnv
+
+result

README.md

@@ -13,7 +13,21 @@ Built for newcomers and coding agents alike.
 
 ## Quick start (pre-release)
 
-Requires a recent Rust toolchain (2024 edition). From a clone:
+### Install with Nix (flake)
+
+```bash
+# Install the CLI into your profile
+nix profile add github:input-output-hk/cardano-init
+
+# Or run it without installing
+nix run github:input-output-hk/cardano-init -- --help
+```
+
+Then invoke `cardano-init` directly (e.g. `cardano-init --name my-protocol --on-chain aiken`).
+
+### From a clone
+
+Requires a recent Rust toolchain (2024 edition).
 
 ```bash
 # Interactive guided setup
@@ -123,3 +137,5 @@ cargo test        # run tests
 cargo fmt         # format
 cargo clippy      # lint
 ```
+
+A Nix flake is provided. Use `nix develop` for a dev shell with the Rust toolchain, or `nix build .#cardano-init` to build the package.

flake.nix

@@ -1,5 +1,5 @@
 {
-  description = "cardano-init — development environment (Rust toolchain)";
+  description = "cardano-init — scaffolds Cardano protocol projects";
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 
@@ -10,7 +10,29 @@
     systems = ["x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin"];
     forAllSystems = f:
       nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
+
+    version = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).package.version;
   in {
+    packages = forAllSystems (pkgs: rec {
+      cardano-init = pkgs.rustPlatform.buildRustPackage {
+        pname = "cardano-init";
+        inherit version;
+
+        src = pkgs.lib.cleanSource self;
+
+        cargoLock.lockFile = ./Cargo.lock;
+
+        meta = with pkgs.lib; {
+          description = "Scaffolds Cardano protocol projects";
+          homepage = "https://github.com/input-output-hk/cardano-init";
+          license = licenses.asl20;
+          mainProgram = "cardano-init";
+        };
+      };
+
+      default = cardano-init;
+    });
+
     devShells = forAllSystems (pkgs: {
       default = pkgs.mkShell {
         packages = with pkgs; [