refactor: simplify Nix configuration and update dependencies

Replaced custom Nerd Fonts overrides with predefined ones. Removed unused Neovim settings and plugins, and disabled Neovim for a specific user. Updated various flake dependencies to their latest versions.

modules/darwin/system/fonts/default.nix

@@ -1,9 +1,8 @@
-{
-  options,
-  config,
-  pkgs,
-  lib,
-  ...
+{ options
+, config
+, pkgs
+, lib
+, ...
 }:
 
 with lib;
@@ -25,16 +24,11 @@ in
 
     fonts = {
       packages =
-        with pkgs;
         [
-          (nerdfonts.override {
-            fonts = [
-              "Hack"
-              "FiraCode"
-              "DroidSansMono"
-              "JetBrainsMono"
-            ];
-          })
+          pkgs.nerd-fonts.hack
+          pkgs.nerd-fonts.fira-code
+          pkgs.nerd-fonts.droid-sans-mono
+          pkgs.nerd-fonts.jetbrains-mono
         ]
         ++ cfg.fonts;
     };