Add Mastra lockfile example and verified case study

[Ayush7614]

Summary

• Adds lockfile-only snapshot examples/mastra/ from mastra-ai/mastra@e9d54b2 (package.json + pnpm-lock.yaml).
• Documents verified baseline scan in website/docs/case-studies/mastra.md (4,555 packages, 64 findings, pnpm audit comparison).
• Hosts Mastra logo at website/static/img/mastra-logo.svg (from repo playground assets).
• Includes Remaining risk, full 64-row Baseline findings table, and Want your project reviewed?

Test plan

• npm run build && node dist/index.js examples/mastra --verbose --all — 64 findings (3 critical · 30 high · 25 medium · 6 low)
• pnpm audit (pnpm 11.3.0, Node 24) — 116 entries documented in case study
• cd website && npm run build — Docusaurus build succeeds

Made with Cursor

[sonukapoor]

Good study for an AI framework monorepo. Four direct findings with two command groups, and the workspace-scoped pnpm add vite@6.3.5 --filter playground is a concrete example of the filtered upgrade pattern. The size comparison to other fixtures in the repo (4,555 packages, largest in the set) is useful context. Single clean commit, all sections present.

[sonukapoor]

After #474 merged today, this PR has conflicts in the shared files (README.md, CHANGELOG.md, examples/readme.md, website/sidebars.ts). Please rebase against main and push:

git fetch upstream
git rebase upstream/main
# resolve any conflicts in README.md, examples/readme.md, sidebars.ts
git push --force-with-lease

The review approval stands — this just needs a clean rebase.