add overlay to lock vscode version, git config into symlink

flake.lock

@@ -187,11 +187,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1788653102,
-        "narHash": "sha256-UHCmPae6q8t15dMGZ6d+Imkpu+tQFxxOWD8+n/5AWT4=",
+        "lastModified": 1788729777,
+        "narHash": "sha256-giJweBm8UNIi56rdA37RkaU7RPCyiU4ml42jPHfIDqc=",
         "ref": "refs/heads/main",
-        "rev": "18982a624707263369598f49f80f55c65357610b",
-        "revCount": 54,
+        "rev": "e4a3a0344d3f0701e26be7fc8a0f271d34058018",
+        "revCount": 55,
         "type": "git",
         "url": "https://git.greyweather.dev/greyweather/nix-helper-flake"
       },