Add Gitea LFS lock fix reference

[cookesan]

Adds Gitea LFS lock fix reference to GHSA-393c-qgvj-3xph.

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/2026/01/GHSA-393c-qgvj-3xph/GHSA-393c-qgvj-3xph.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]

Refreshed on July 8, 2026:

• GHSA-393c-qgvj-3xph and CVE-2026-20897 remain public and consistent with this advisory.
• Verified go-gitea/gitea PRs #36344 and #36349, commits da036f3f35ca830b22cf4480912ed261303b798f and 2c778ff06729443be0ab227f3b183074cdaf4fdc, release v1.25.4, and the Go module proxy record for github.com/go-gitea/gitea v1.25.4.
• Local validation passed: jq empty and git diff --check.

No affected range, package, or severity changes are included.