Require rspec to pass for rails 8

[rsmithlal]

Summary

Describe the change and the motivation.

Checklist

• Tests added/updated and passing (bin/ci).
• Lint and security checks (rubocop, brakeman, bundler-audit).
• Documentation updated under docs/ describing new/changed functionality.
• Mermaid diagrams (docs/*.mmd) updated to reflect changes.
• Rendered PNGs regenerated with bin/render_diagrams and committed.
• For DB changes, included any needed backfills/dedupes and noted risks.

Screenshots / Diagrams

If applicable, include screenshots or link to updated diagrams.

Notes

Anything reviewers should be aware of (migration order, flags, feature toggles).