add overlay to lock vscode version, git config into symlink

modules/overlays.nix

@@ -0,0 +1,21 @@
+{ inputs, self, ... }: let
+  overlays = [
+    (final: prev: let
+      stablePkgs = import inputs.nixpkgs-26-05 {
+        system = prev.stdenv.hostPlatform.system;
+        config.allowUnfree = true;
+      };
+    in {
+      vscode = stablePkgs.vscode;
+      biri = self.packages.${prev.stdenv.hostPlatform.system}.biri;
+    })
+  ];
+in {
+  flake.nixosModules.global = { ... }: {
+    nixpkgs.overlays = overlays;
+  };
+
+  flake.homeModules.global = { lib, config, ... }: {
+    nixpkgs.overlays = lib.mkIf (config.info.isStandalone) overlays;
+  };
+}