nixvim: add lazygit and diffview plugins with keymaps

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

modules/home/nixvim/plugins/editor/git.nix

@@ -0,0 +1,10 @@
+{ pkgs, ... }: {
+  programs.nixvim = {
+    extraPackages = [ pkgs.lazygit ];
+
+    plugins = {
+      lazygit.enable = true;
+      diffview.enable = true;
+    };
+  };
+}