Add Agentic RAG example with DeepSecure integration

[SidPatel151]

🤖 New Example: Agentic RAG with DeepSecure

This PR adds a comprehensive Agentic RAG (Retrieval-Augmented Generation) example that demonstrates:

🔐 Security Features

• Secure API key management via DeepSecure vault
• CLI bridge pattern for robust secret retrieval
• Environment authentication (bypasses keychain issues)
• Agent identity audit trails

🧠 Technical Features

• Complete LangGraph workflow with query generation, document grading, and answer synthesis
• Web document processing (Lilian Weng's blog posts)
• Integration with Novita LLM API
• Advanced text chunking and vector storage

📁 Files Added

• examples/08_agentic_rag_with_deepsecure.py - Complete working example
• Updated examples/README.md - Full documentation with setup instructions

🧪 Tested & Working

• ✅ DeepSecure authentication
• ✅ Secret retrieval from vault
• ✅ Document processing pipeline
• ✅ LLM API integration
• ✅ End-to-end RAG workflow

Perfect for developers wanting to see real-world DeepSecure integration with modern AI frameworks!