refactor config with better structure

nixos/desktop/fonts.nix

@@ -0,0 +1,17 @@
+{ pkgs, ... }:
+{
+  fonts = {
+    packages = with pkgs; [
+      nerd-fonts.iosevka
+      nerd-fonts.symbols-only
+    ];
+    fontconfig = {
+      enable = true;
+      defaultFonts = {
+        emoji = [
+
+        ];
+      };
+    };
+  };
+}