Add nix flake with devshell and direnv

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -54,3 +54,6 @@ pids
 
 # Diagnostic reports (https://nodejs.org/api/report.html)
 report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+
+# Direnv cache
+.direnv

flake.lock

@@ -0,0 +1,57 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 0,
+        "narHash": "sha256-Tbk1MZbtV2s5aG+iM99U8FqwxU/YNArMcWAv6clcsBc=",
+        "path": "/nix/store/l9nb64iii15y0nr37qrs1cfm6rlpg6gh-source",
+        "type": "path"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "utils": "utils"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
+    "utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,17 @@
+{
+  inputs = {
+    utils.url = "github:numtide/flake-utils";
+  };
+  outputs = { self, nixpkgs, utils }: utils.lib.eachDefaultSystem (system:
+    let
+      pkgs = nixpkgs.legacyPackages.${system};
+    in
+    {
+      devShell = pkgs.mkShell {
+        buildInputs = with pkgs; [
+          nest-cli
+        ];
+      };
+    }
+  );
+}