Add LiquidJS symlink root fix reference

[cookesan]

Adds LiquidJS symlink root fix reference to GHSA-56p5-8mhr-2fph.

Audit refresh, July 8, 2026:

• Confirmed the live PR is open, ready for review, merge-clean, and the visible advisory check is green.
• Rechecked the merge-base diff: exactly one advisory JSON file changes (advisories/github-reviewed/2026/04/GHSA-56p5-8mhr-2fph/GHSA-56p5-8mhr-2fph.json), JSON parses, git diff --check passes, and the exact-head worktree is clean.
• Revalidated the added public references in the diff; all resolve through their source site or registry.

[cookesan]

Rechecked this reference-only PR while keeping the open Advisory Database queue current.

• The patch only adds the LiquidJS symlink root fix commit reference; it does not change affected ranges, package metadata, or severity.
• The commit resolves to 529dd67eeb6b125637623d6a723601f0938d3613.
• The commit subject matches the advisory context: fix: use realpath for fs.contains (#867).

No other advisory fields are changed.