refactor flake.nix and osConfig organization

modules/vim.nix

@@ -3,6 +3,7 @@
 {
   home.packages = with pkgs;[
   	clang-tools
+	nixd
 	nodejs_23
   ];
 

modules/yubikey.nix

@@ -1,14 +0,0 @@
-{ config, lib, inputs, pkgs, ... }:
-
-{
-  programs.gnupg.agent = {
-    enable = true;
-    enableSSHSupport = true;
-  };
-
-  security.pam.yubico = {
-    enable = true;
-    id = "30536547";
-    mode = "challenge-response";
-  };
-}