Modules: Deprecate agenix module (replace with sops-nix)

system/modules/1_deprecated/agenix/options.nix

@@ -0,0 +1,22 @@
+{
+  lib,
+  mylib,
+  ...
+}: {
+  secrets = lib.mkOption {
+    type = lib.types.attrs;
+    description = "The secret files managed by agenix (encrypted by SSH key)";
+    example = ''
+      {
+        christoph = [
+          "heidi-discord-token"
+          "kopia-password"
+          "kopia-server-username"
+          "kopia-server-password"
+        ];
+      }
+    '';
+
+    default = {};
+  };
+}