[nix] Cleans up warnings about options and reduces duplication

home-manager/features/linux-desktop.nix

@@ -3,7 +3,6 @@
   imports = [
     ./audio.nix
     ./hyprland.nix
-    ./nix.nix
     ./rofi/rofi.nix
     ./sway.nix
     ../apps/element.nix

home-manager/features/nix.nix

@@ -1,10 +0,0 @@
-{ pkgs, ... }:
-{
-  # Enable flakes and nix-commnands.
-  nix.settings.experimental-features = ["flakes" "nix-command"];
-
-  # Allow unfree code
-  nixpkgs.config = {
-    allowUnfree = true;
-  };
-}

home-manager/features/shell.nix

@@ -48,7 +48,7 @@
       PATH=$PATH:$HOME/.local/bin
       GITHUB_USERNAME=periodic
     '';
-    initExtra = ''
+    initContent = ''
       # Make ^U work like it does in Bash
       bindkey "^U" backward-kill-line