Add Zep memory integration documentation

[jackaldenryan]

Summary

• Add comprehensive Zep memory integration documentation to the memory notebook
• Include both ZepUserMemory and ZepGraphMemory examples
• Add setup instructions, configuration options, and use cases
• Include proper resource cleanup and serialization examples

Changes

• Added complete Zep memory section to python/docs/src/user-guide/agentchat-user-guide/memory.ipynb
• Documented ZepUserMemory for persistent conversation context
• Documented ZepGraphMemory for structured knowledge representation
• Added installation instructions: pip install zep-autogen
• Added environment variable setup for API keys
• Included working code examples with proper error handling
• Added configuration options and best practices

Test Plan

• [x] Validated all imports work correctly in isolated environment
• [x] Verified package installation process
• [x] Tested code examples syntax and structure
• [x] Confirmed integration with AutoGen Memory protocol
• [x] Documented cleanup procedures

🤖 Generated with Claude Code

[jackaldenryan]

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