feat: make nh host selection automatic

README.md

@@ -11,7 +11,7 @@ nix run .#home-manager -- switch --flake .#<username>@<host>
 `nh` 導入後:
 
 ```
-nh os switch -H <host>
+nh os switch
 
-nh home switch -c <username>@<host>
+nh home switch
 ```

hosts/default.nix

@@ -5,6 +5,11 @@ rec {
     x1carbon = import ./x1carbon inputs;
     fungus = import ./fungus inputs;
   };
-  nixos = builtins.mapAttrs (_: host: host.nixos) hosts;
+  nixos = builtins.listToAttrs (
+    map (host: {
+      name = host.hostname;
+      value = host.nixos;
+    }) (builtins.attrValues hosts)
+  );
   home-manager = builtins.foldl' (a: b: a // b) { } (map (h: h.home-manager) (builtins.attrValues hosts));
 }

hosts/mkHost.nix

@@ -12,6 +12,8 @@ let
   };
 in
 {
+  inherit hostname;
+
   nixos = inputs.nixpkgs.lib.nixosSystem {
     modules =
       systemModules