docs: add architecture diagram and dynamic contributors section to README

[Vi-bha]

Added Mermaid architecture diagram showing the complete request lifecycle across all three services (React, Express, FastAPI + FAISS), and a dynamic contributors section using contrib.rocks that auto-updates when new contributors join.

[FireFistisDead]

@Vi-bha the contributo section is here

but you made another contributors section in the last which is here

and also there are 2 contributors shown but repo has more contributors and also i said that the section should dynamically add contributors if anoter new contributor comes

[Krishnapriya1911]

Hi @Vi-bha 👋

This documentation improvement looks really helpful for the project. I would love to contribute further enhancements under GSSoC'26.

I can help with:
• Improving README structure and formatting
• Adding better architecture/workflow diagrams
• Enhancing setup instructions and contributor guidance
• Improving responsiveness/visual organization of documentation
• Adding additional API/project flow explanations

Please let me know if I can work on a follow-up contribution or related enhancement. 🚀

[FireFistisDead]

@Vi-bha whats he update?

[FireFistisDead]

@Vi-bha ??