feat: Add NGUI end-to-end example with improved configuration and docs

[Hrithik-Gavankar]

Summary

Added a complete end-to-end example demonstrating the Next Gen UI system with improved configuration and comprehensive documentation.

Changes

• ✨ New Demo: Added React Vite project with OneCard component demo
• 📚 Enhanced README: Added complete setup instructions for Ollama, backend, and frontend
• 🔧 Configurable Backend: Made main.py generic to support different AI models (Ollama, OpenAI, etc.)
• 📖 Configuration Guide: Added MODEL_CONFIGURATION.md with setup examples
• 🔗 Fixed Imports: Updated DynamicComponent import for npm-linked UI package

How to Test

1. Install Ollama: ollama pull llama3.2:3b
2. Start backend: uvicorn main:app --reload
3. Start frontend: npm run dev (in NGUI-e2e folder)
4. Test the complete chat → AI → UI generation flow

Benefits

• 🚀 Easy setup for new contributors
• 🎛️ Flexible model configuration
• 📋 Complete working example
• 📝 Clear documentation