feat: add nix-direnv

modules/home/base.nix

@@ -8,6 +8,7 @@
     ./devtools/ai-tools.nix
     ./devtools/languages.nix
     ./devtools/default.nix
+    ./devtools/direnv.nix
     ./devtools/try.nix
     ./secrets.nix
   ];
@@ -34,6 +35,8 @@
       path = "~/src/tries";
     };
 
+    rsydn.direnv.enable = lib.mkDefault true;
+
     rsydn.devTools = {
       enable = lib.mkDefault true;
       packages = with pkgs; [

modules/home/devtools/direnv.nix

@@ -0,0 +1,27 @@
+{ config, lib, ... }:
+let
+  inherit (lib) mkOption types mkIf;
+  cfg = config.rsydn.direnv;
+in {
+  options.rsydn.direnv = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Enable direnv with nix-direnv for automatic devshell activation.";
+    };
+    silent = mkOption {
+      type = types.bool;
+      default = true;
+      description = "Suppress direnv loading messages.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    programs.direnv = {
+      enable = true;
+      enableNushellIntegration = true;
+      nix-direnv.enable = true;
+      silent = cfg.silent;
+    };
+  };
+}