npm audit fails on the docs site: sharp below 0.35.5 (GHSA-wq5f-xc86-pv6w) #2000

The "Audit npm deps" job (audit.yml) fails on the docs site: npm audit --audit-level=high reports 14 advisories, one high, GHSA-wq5f-xc86-pv6w (sharp below 0.35.5, a librsvg flaw, CVE-2026-96889). Seen on PR #1996's run https://github.com/messagecrate/message-crate/actions/runs/37804851417, which changed no lockfile; main will report the same at its next audit. Fix: update sharp (an Astro Starlight dependency) in docs/package-lock.json and check the remaining moderate advisories while there.