nix: set up tooling

nix/package.nix

@@ -0,0 +1,24 @@
+{
+  lib,
+  buildGoModule,
+}: let
+  fs = lib.fileset;
+  s = ../.;
+in
+  buildGoModule {
+    pname = "tct";
+    version = "0.1.0";
+
+    src = fs.toSource {
+      root = s;
+      fileset = fs.unions [
+        (fs.fileFilter (file: builtins.any file.hasExt ["go"]) s)
+        ../go.mod
+        ../go.sum
+      ];
+    };
+
+    vendorHash = "sha256-m5mBubfbXXqXKsygF5j7cHEY+bXhAMcXUts5KBKoLzM=";
+
+    ldflags = ["-s" "-w"];
+  }