hosts: define hostPlatform in defined systems

instead of getting them impurely from `builtins.currentSystem`

hosts/main/default.nix

@@ -83,6 +83,8 @@
       OLLAMA_HOST = "127.0.0.1:${builtins.toString config.services.ollama.port}";
     };
 
+    nixpkgs.hostPlatform = "x86_64-linux";
+
     system.stateVersion = "23.05";
   };
 }

hosts/tablet.nix

@@ -52,6 +52,8 @@
       lidSwitchExternalPower = "lock";
     };
 
+    nixpkgs.hostPlatform = "x86_64-linux";
+
     system.stateVersion = "23.11";
   };
 }

hosts/vm-base.nix

@@ -20,5 +20,6 @@
     virtualisation.forwardPorts = [
       { from = "host"; host.port = 2222; guest.port = 22; }
     ];
+    nixpkgs.hostPlatform = "x86_64-linux";
   };
 }

outputs.nix

@@ -43,6 +43,7 @@ self = {
     nixosSystem = import "${inputs.nixpkgs}/nixos/lib/eval-config.nix";
     mkNixosSystem = path: nixosSystem {
       inherit lib;
+      system = null;
       modules = [
         path
         {