Simplify nixos-* justfile recipes

Make the hostname configurable for NixOS and remove the need to specify
the profile name when running `nixos-rebuild` commands as the hostname
can be used.

flake.nix

@@ -30,8 +30,8 @@
         lib = import ./lib { inherit inputs; };
 
         nixosConfigurations = {
-          apollo = mkNixos { desktop = true; };
-          nixedo = mkNixos { desktop = true; };
+          apollo = mkNixos { desktop = true; hostname = "apollo"; };
+          nixedo = mkNixos { desktop = true; hostname = "nixedo"; };
         };
 
         homeConfigurations = { wsl2 = mkWsl; };

justfile

@@ -1,16 +1,18 @@
+profile := `hostname`
+
 _default:
     just --list
 
 check:
     nix flake check
 
-nixos-build profile:
+nixos-build:
     sudo nixos-rebuild build --flake ".#{{ profile }}"
 
-nixos-switch profile:
+nixos-switch:
     sudo nixos-rebuild switch --flake ".#{{ profile }}"
 
-nixos-test profile:
+nixos-test:
     sudo nixos-rebuild test --flake ".#{{ profile }}"
 
 update:

lib/nixos/configuration.nix

@@ -1,4 +1,4 @@
-{ inputs, desktop ? false, self, }:
+{ inputs, desktop ? false, hostname, self }:
 { pkgs, ... }:
 let
   configure-gtk = pkgs.writeTextFile {
@@ -30,7 +30,8 @@ in {
     DefaultTimeoutStopSec=10s
   '';
 
-  # networking.hostName = hostname;
+  networking.hostName = hostname;
+
   # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
 
   # Configure network proxy if necessary

lib/nixos/default.nix

@@ -1,7 +1,7 @@
-{ inputs, self, username, }:
-{ desktop ? false, }:
+{ inputs, self, username }:
+{ desktop ? false, hostname }:
 let
-  configuration = import ./configuration.nix { inherit desktop inputs self; };
+  configuration = import ./configuration.nix { inherit desktop hostname inputs self; };
   hardwareConfiguration = import ./hardware-configuration.nix;
 in inputs.nixpkgs.lib.nixosSystem {
   modules = [