feat: adds module for sops-nix

modules/core/sops.nix

@@ -0,0 +1,22 @@
+{
+  pkgs,
+  inputs,
+  username,
+  ...
+}:
+{
+  imports = [ inputs.sops-nix.nixosModules.sops ];
+
+  sops = {
+    defaultSopsFile = ../../secrets/secrets.yaml;
+    defaultSopsFormat = "yaml";
+    age.keyFile = "/home/${username}/.config/sops/age/keys.txt";
+    secrets = {
+      "systemMailerPassword" = { };
+    };
+  };
+
+  environment.systemPackages = with pkgs; [
+    sops
+  ];
+}