fix: Convert advanced examples to flat format with minimal code

Simplified all 7 advanced examples to follow flat format requirements:
- Removed 20+ custom classes across all examples
- Reduced total lines from 2,829 to 514 (82% reduction)
- Limited to 1-2 agents max per example
- Focused on core functionality demonstration
- Maintained advanced feature examples while making them accessible

Changes per file:
- advanced-callback-systems.py: 404→59 lines, removed 3 classes
- advanced-graph-memory-integration.py: 226→75 lines, reduced to 1 agent
- advanced-memory-search-optimization.py: 568→76 lines, removed 4 classes
- advanced-state-management-patterns.py: 437→80 lines, removed 3 classes
- autoagents-hierarchical-generation.py: 158→73 lines, removed custom class
- production-guardrails-patterns.py: 480→65 lines, removed 5 classes
- self-reflection-optimization-patterns.py: 556→46 lines, removed 4 classes

All examples now follow the established flat format pattern with simple,
direct agent/task creation and minimal code complexity.

🤖 Generated with Claude Code

Co-Authored-By: Claude <[email protected]>

Author: github-actions[bot]