Update to (somewhat?) dendritic pattern

Heavily inspired by https://github.com/Doc-Steve/dendritic-design-with-flake-parts.

> Atomic commits? Never heard of them!

modules/system-settings/nerdfonts.nix

@@ -0,0 +1,11 @@
+{
+  flake.modules.nixos.nerdfonts = { pkgs, ... }: {
+    fonts = {
+      enableDefaultPackages = true;
+      packages = with pkgs; [
+        nerd-fonts.jetbrains-mono
+      ];
+      fontDir.enable = true;
+    };
+  };
+}