docs: restructure research agent notebook (#271)

* docs: restructure research agent notebook with comprehensive explanations and examples

Reorganized the notebook to improve pedagogical flow and add detailed guidance:

- Added introduction explaining why research agents are ideal agentic use cases
- Included prerequisites section with required knowledge and setup instructions
- Expanded stateless query example with output visualization and detailed explanations
- Clarified when to use stateless vs stateful agent patterns
- Enhanced production-ready improvements section with three key enhancements
- Added stateful agent example using ClaudeSDKClient with conversation memory
- Improved conclusion with clear learning outcomes and next steps
- Updated kernel specification to match current environment

* Update 00_The_one_liner_research_agent.ipynb

Author: PedramNavid