use acer-wmi-ext overlay from source repo

lib/mkNixosSystem.nix

@@ -8,6 +8,7 @@
   claude-code,
   nix-sweep,
   peerix,
+  acer-wmi-ext,
   ...
 }:
 hardwareConfig: hostConfig:
@@ -17,10 +18,14 @@ nixpkgs.lib.nixosSystem {
   specialArgs = {
     inherit nix-flatpak;
     inherit plasma-manager;
+    inherit acer-wmi-ext;
   };
   modules = [
     {
-      nixpkgs.overlays = [ claude-code.overlays.default ];
+      nixpkgs.overlays = [
+        claude-code.overlays.default
+        acer-wmi-ext.overlays.default
+      ];
       nix.settings = {
         substituters = [ "https://claude-code.cachix.org" ];
         trusted-public-keys = [ "claude-code.cachix.org-1:YeXf2aNu7UTX8Vwrze0za1WEDS+4DuI2kVeWEE4fsRk=" ];