Move disabling wifi power saving to a host-specific file.

nix/configuration/hosts/odo/wifi.nix

@@ -0,0 +1,16 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  imports = [ ];
+
+  config = {
+    environment.loginShellInit = lib.mkIf (!config.me.buildingIso) ''
+      doas iw dev wlan0 set power_save off
+    '';
+  };
+}