Add configs/ folder: Firefox prefs via autoconfig, Gruvbox fastfetch

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

modules/fastfetch.nix

@@ -0,0 +1,7 @@
+{ config, pkgs, ... }:
+
+{
+  # System-wide config; fastfetch searches /etc/xdg/fastfetch/ after
+  # ~/.config/fastfetch/, so a user config there would still win.
+  environment.etc."xdg/fastfetch/config.jsonc".source = ../configs/fastfetch/config.jsonc;
+}

modules/firefox.nix

@@ -0,0 +1,11 @@
+{ config, pkgs, ... }:
+
+{
+  programs.firefox = {
+    enable = true;
+    # Not locked: values are reapplied on every Firefox start, but can be
+    # changed in the UI for the current session. (Read as text: the module
+    # doesn't copy autoConfigFiles paths into the store.)
+    autoConfig = builtins.readFile ../configs/firefox/prefs.js;
+  };
+}

modules/users.nix

@@ -9,7 +9,6 @@
   };
 
   programs.zsh.enable = true;
-  programs.firefox.enable = true;
 
   programs.steam = {
     enable = true;