Standardize go project structure

.gitignore

@@ -1 +1,2 @@
 /reaction.db
+/result

default.nix

@@ -0,0 +1,18 @@
+{ buildGoModule, fetchFromGitLab }:
+let
+  pname = "reaction";
+  version = "v0.1";
+in buildGoModule {
+  inherit pname version;
+
+  src = ./.;
+  # src = fetchFromGitLab {
+  #   domain = "framagit.org";
+  #   owner = "ppom";
+  #   repo = pname;
+  #   rev = version;
+  #   sha256 = "sha256-45ytTNZIbTIUOPBgAdD7o9hyWlJo//izUhGe53PcwNA=";
+  # };
+
+  vendorHash = "sha256-g+yaVIx4jxpAQ/+WrGKxhVeliYx7nLQe/zsGpxV4Fn4=";
+}