add: more system modules

system/modules/user/shell/fish/default.nix

@@ -0,0 +1,19 @@
+{ pkgs, lib, config, ... }:
+
+let
+  cfg = config.systemModules.user.shell.fish;
+in
+
+{
+  config = lib.mkIf cfg.enable {
+    users.users.ooks.shell = pkgs.fish;
+    programs.fish = {
+      enable = true;
+      vendor = {
+        completions.enable = true;
+        config.enable = true;
+        functions.enable = true;
+      };
+    };
+  };
+}