Add Gitea private project fix references

[cookesan]

Adds Gitea private project fix references to GHSA-7xq4-mwcp-q8fx.

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/2025/12/GHSA-7xq4-mwcp-q8fx/GHSA-7xq4-mwcp-q8fx.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-7xq4-mwcp-q8fx and CVE-2025-68945 remain public and consistent with this advisory.
• Verified go-gitea/gitea PRs #28423 and #28432, commit 265f485295e1bab4d6bf4aabec6e782fd1174d2f, release v1.21.2, and the Go module proxy record for code.gitea.io/gitea v1.21.2.
• Local validation passed: jq empty and git diff --check.

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