refactor: extract host config into 'host.nix' files

hosts/vm/default.nix

@@ -10,6 +10,7 @@
     inputs.disko.nixosModules.disko
     ../../modules/common
     ./hard.nix
+    ./host.nix
     inputs.sops-nix.nixosModules.sops
     ./disk.nix
     ../../modules/boot/bootloader.nix
@@ -22,16 +23,12 @@
     ../../modules/fonts
     ../../modules/ssh
     ../../modules/storage
+    ../../modules/stylix
     (import ../../modules/secrets {
       inherit lib inputs config;
     })
   ];
 
-  host = {
-    username = "h";
-    name = "vm";
-  };
-
   home-manager.users.${config.host.username} = import ../../home/hosts/vm {
     inherit inputs config pkgs;
   };