feat(backend): initialize specialized documentation for nodejs

[beginwebdev2002]

Initialized comprehensive "Best Practices & Production-Ready Patterns" for Node.js in backend/nodejs/readme.md, incorporating architectural guidelines, performance optimization, error handling, and security measures. The document is structured for "Vibe Coding" compatibility. Also linked this new documentation to the main backend/readme.md directory.

---

PR created automatically by Jules for task 13864094766170993635 started by @beginwebdev2002

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.