Add comprehensive README documentation

[Copilot]

Replaced the default Next.js README template with project-specific documentation for the RAGBot electronics recommendation system.

Changes

• Project Overview: Added description of RAG-based chatbot architecture with technology badges (Next.js 15, TypeScript, LangChain, ChromaDB)
• Features: Documented core functionality (RAG chat, document analysis, vector search), UI capabilities (markdown support, responsive design), admin features (user management, analytics, logs), and security (NextAuth, bcrypt)
• Setup Guide: Added installation steps, environment variable configuration (Gemini API, ChromaDB, MongoDB), and ChromaDB deployment instructions
• Project Structure: Included annotated directory tree showing API routes, components, utilities, and middleware organization
• Usage Examples: Provided sample queries for electronics recommendations and document analysis workflows
• Admin Documentation: Described dashboard routes for user management, chatbot configuration, analytics, and activity logs
• API Reference: Listed available endpoints for chat, authentication, and chatbot management

Technical Details

The application uses:

• LangChain retrieval chains with Google Gemini embeddings (text-embedding-004) and chat models (gemini-1.5-flash)
• ChromaDB for vector storage with configurable collection names
• RecursiveCharacterTextSplitter for document processing (CSV, PDF, TXT)
• History-aware retriever for context maintenance across conversation turns

Original prompt

Can you add a comprehensive Readme.md file to this repository?

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