docs: move the Toolbox page to /quickstart/toolbox

The page was renamed to Toolbox but kept the our-tools filename, so its URL
still read /quickstart/our-tools. Renamed the file to match and repointed the
SUMMARY entry.

The old path answered 200, so .gitbook.yaml now redirects it to the new one
rather than leaving a dead link behind.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Lookov