Broken Link: references/testability.md#AV1620

[github-actions]

Docusaurus reported a broken link while building docs.fallout.build.

• Broken link: references/testability.md#AV1620
• First detected by deploy run: https://github.com/Fallout-build/docs.fallout.build/actions/runs/28353531675

The markdown source-of-truth lives in Fallout-build/Fallout under docs/ (or this repo's Docusaurus config). Fix the reference there and close this issue.

Opened automatically by the deploy workflow. One issue is kept open per unique broken link — recurrences do not open duplicates.