Add netty worktree helpers

Add netty-specific worktree helper commands and a zsh wrapper that creates sibling worktrees and cds into them.

Also split script packaging so Darwin keeps the existing wt integration while netty gets git-worktree-based helpers.

Co-authored-by: Codex <noreply@openai.com>

home/netty-worktree.nix

@@ -0,0 +1,23 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  customScripts = import ../scripts {inherit config lib pkgs;};
+in {
+  home.packages = builtins.attrValues customScripts.nettyPackages;
+
+  programs.zsh.initContent = lib.mkAfter ''
+    wtc() {
+      if [[ $# -ne 1 ]]; then
+        printf 'usage: wtc <worktree-name>\n' >&2
+        return 1
+      fi
+
+      local worktree_path
+      worktree_path=$(command wt-create "$1") || return
+      cd -- "$worktree_path" || return
+    }
+  '';
+}