Re-add vim-fugitive

modules/nixvim/fugitive.nix

@@ -0,0 +1,18 @@
+{
+  flake.modules.nixvim.custom = {
+    plugins.fugitive.enable = true;
+
+    keymaps = [
+      {
+        key = "<leader>gc";
+        action = "<cmd>Git commit<CR><C-w>K";
+      }
+
+      {
+        # Open the ":Git" window in its own buffer, not a split.
+        key = "<leader>gs";
+        action = "<cmd>0Git<CR>";
+      }
+    ];
+  };
+}