NPM 12 needs approval for postinstall

With the release of NPM 12, [lifecycle scripts now need explicit approval for execution](https://github.blog/changelog/2026-06-09-upcoming-breaking-changes-for-npm-v12/), meaning the installation of Claude Code with this feature will not work out of the box for anyone using NPM 12 or future versions.

I know that this will become obsolete with #36 resp. #37 but until then, see attached PR #44 for a quick fix