feat: install agenix as a home-manager module

modules/home-manager/default.nix

@@ -8,6 +8,7 @@ in
   imports = (featureBundler ./bundles) ++ (featureBundler ./features);
 
   # keep-sorted start
+  agenix.enable = lib.mkDefault true;
   bat.enable = lib.mkDefault true;
   direnv.enable = lib.mkDefault true;
   eza.enable = lib.mkDefault true;

modules/home-manager/features/agenix.nix

@@ -0,0 +1,16 @@
+{
+  config,
+  lib,
+  userName,
+  ...
+}:
+let
+  feature = "agenix";
+in
+{
+  config = lib.mkIf config.${feature}.enable {
+    age.identityPaths = [ "/home/${userName}/.ssh/id_ed25519" ];
+  };
+
+  options.${feature}.enable = lib.mkEnableOption "enables ${feature}";
+}