examples: add pizzaz FastApps demo

[chasehuh]

Summary

• add a complete FastApps port of the OpenAI Apps SDK “Pizzaz” gallery under examples/pizzaz (see https://github.com/openai/openai-apps-sdk-examples/tree/main/src/pizzaz)
• cover five widgets (map, carousel, albums, list, shop) plus shared React utilities with Tailwind 4 + Vite 6 (Node.js 18+) and a custom build script
• document the example (including Mapbox token guidance) and link it from the main README; lockfile (package-lock.json) is committed for reproducible installs

Testing

• black examples/pizzaz/server
• ruff check examples/pizzaz/server
• pytest
• examples/pizzaz: npm install && npm run build
• examples/pizzaz: fastapps build
• fastapps dev (verified MCP endpoint reachable at /mcp)

Notes

• Mapbox uses the public demo token bundled with the original Apps SDK example; README explains how/when to replace it with your own token for production.
• Tailwind 4 requires the custom build-all.mts shipped with the example (FastApps CLI automatically calls it via fastapps build).
• This is my first PR to FastApps, so please let me know if anything looks off and I’ll adjust right away.

[chasehuh]

Closing this PR as the implementation was based on a deprecated framework and has structural issues. I’ll rewrite the code with an updated stack and submit a new PR.