darwin,users: modify user config structure

flakes/darwin/users/default.nix

@@ -2,6 +2,6 @@
 
 {
   imports = [
-    ./guanranwang.nix
+    ./normal-users/guanranwang.nix
   ];
 }

flakes/darwin/users/guanranwang.nix

@@ -1,10 +0,0 @@
-{ pkgs, ... }:
-
-{
-  users.users.guanranwang = {
-    createHome = true;
-    description = "Guanran Wang";
-    home = "/Users/guanranwang";
-    shell = pkgs.fish;
-  };
-}

flakes/darwin/users/normal-users/guanranwang.nix

@@ -0,0 +1,14 @@
+{ pkgs, ... }:
+
+{
+  users = {
+    knownUsers = [ "guanranwang" ];
+    users."guanranwang" = {
+      createHome = true;
+      description = "Guanran Wang";
+      home = "/Users/guanranwang";
+      shell = pkgs.fish;
+      uid = 501;
+    };
+  };
+}