add core configuration

modules/common/nixcommon.nix

@@ -0,0 +1,49 @@
+{
+  inputs,
+  outputs,
+  config,
+  pkgs,
+  ...
+}: {
+  nixpkgs.config.allowUnfree = true;
+
+  home-manager = {
+    extraSpecialArgs = {inherit inputs outputs;};
+    useGlobalPkgs = true;
+    useUserPackages = true;
+  };
+
+  nix = {
+    nixPath = ["nixpkgs=${inputs.nixpkgs}"];
+    package = pkgs.nixVersions.stable;
+    optimise.automatic = true;
+    gc = {
+      persistent = true;
+      automatic = true;
+    };
+    extraOptions = ''
+      # If set to true, Nix will fall back to building from source if a binary substitute fails.
+      fallback = true
+      # the timeout (in seconds) for establishing connections in the binary cache substituter.
+      connect-timeout = 10
+      # these log lines are only shown on a failed build
+      log-lines = 25
+    '';
+    settings = {
+      auto-optimise-store = true;
+
+      trusted-users = ["root" "@wheel"];
+      experimental-features = [
+        "nix-command"
+        "flakes"
+      ];
+    };
+  };
+  # This value determines the NixOS release from which the default
+  # settings for stateful data, like file locations and database versions
+  # on your system were taken. It‘s perfectly fine and recommended to leave
+  # this value at the release version of the first install of this system.
+  # Before changing this value read the documentation for this option
+  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
+  system.stateVersion = "24.11";
+}