♻️ refactor layout, simplify flake.nix

nix/checks.nix

@@ -0,0 +1,12 @@
+{ self, system, pre-commit-hooks, ... }:
+with self.pkgs.${system};
+{
+  pre-commit-check = pre-commit-hooks.lib.${system}.run {
+    src = ./.;
+    hooks = {
+      deadnix.enable = true;
+      nixpkgs-fmt.enable = true;
+      statix.enable = true;
+    };
+  };
+} // (deploy-rs.lib.deployChecks self.deploy)