Refactor user option types across modules for consistency

Updated multiple configuration files to replace the user option type with a unified `usersOptionType`, enhancing consistency in user management across applications and services. This change simplifies the user configuration process and improves maintainability.

modules/dev/zig.nix

@@ -18,9 +18,8 @@ in
     my.dev.zig = {
       enable = lib.mkEnableOption "Install Zig tooling globally";
       users = lib.mkOption {
-        type = lib.types.either lib.types.str (lib.types.listOf lib.types.str);
+        type = inputs.self.lib.usersOptionType lib;
         default = config.my.toggleUsers.dev;
-        merge = inputs.self.lib.mergeUsersOption lib;
         description = "Users to install Zig packages for";
       };
     };