nix: initial tooling; add NixOS module

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I5ff8dfa450ec405e2ead5d16e0de90856a6a6964

flake.nix

@@ -0,0 +1,36 @@
+{
+  description = "Troutbot - GitHub webhook bot";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-unstable";
+
+  outputs = {
+    self,
+    nixpkgs,
+  }: let
+    systems = [
+      "x86_64-linux"
+      "aarch64-linux"
+      "x86_64-darwin"
+      "aarch64-darwin"
+    ];
+
+    forEachSystem = f: nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
+  in {
+    nixosModules = {
+      troutbot = import ./nix/modules/nixos.nix self;
+      default = self.nixosModules.troutbot;
+    };
+
+    packages = forEachSystem (pkgs: {
+      troutbot = pkgs.callPackage ./nix/package.nix {};
+      default = self.packages.${pkgs.hostPlatform.system}.troutbot;
+    });
+
+    devShells = forEachSystem (pkgs: {
+      default = pkgs.mkShell {
+        name = "troutbot-dev";
+        packages = [pkgs.nodejs-slim pkgs.pnpm];
+      };
+    });
+  };
+}