fix(nix): bring up to feature parity

nix/modules/cli/git.nix

@@ -1,9 +1,14 @@
+{ config, ... }:
+let
+  inherit (config.flake) manifest;
+in
 {
   flake.modules.homeManager.default =
-    { manifest, config, ... }:
+    { config, ... }:
     {
       home.sessionVariables.GIT_CONFIG_GLOBAL = "$HOME/.config/git/config";
       programs.git = {
+        enable = true;
         userName = manifest.users.${config.home.username}.name;
         userEmail = manifest.users.${config.home.username}.email;
         signing.key = "~/.ssh/id_ed25519.pub";

nix/modules/cli/nix.nix

@@ -0,0 +1,6 @@
+{
+  flake.modules.nixos.default.nix.settings.experimental-features = [
+    "nix-command"
+    "flakes"
+  ];
+}