Add Apartment Finder cookbook

[lukaslevert]

Summary

• add Elijah Jacob’s Apartment Finder as a self-contained Next.js recipe
• register it in the main cookbook index and website catalog
• preserve the original MIT license, notice, source attribution, and live demo
• refresh dependencies and scope Next.js build tracing for the cookbook monorepo

Security

• copied no local environment files or repository metadata
• committed only .env.example with a placeholder key
• passed the repository’s gitleaks and private-key pre-commit hooks on the staged files
• npm audit reports 0 vulnerabilities
• documented that public deployments need authentication and rate limiting

Verification

• npm ci
• npm run lint
• npm run build
• npm audit
• pre-commit run --all-files
• cookbook catalog validated against website/cookbook.schema.json
• live demo and Open Graph image both return HTTP 200

Original project: https://github.com/elijahgjacob/apartment-finder-web